For me, at least! LOL!

This caveat should be unnecessary, but my friendly counsel advises me to post it and so I will:
"The results obtained here are true and valid for the rifle, scope, shooter and setup in question. No warranties, express, or implied, are given.
Readers are advised to test and confirm that the components and settings work in their respective rifles before committing to any action where accuracy is of prime importance.
Ct Custom Airguns strongly suggests that each shooter tests his/her system and then decide accordingly"

Phew!  OK, let's get started:

I've been shooting quite extensively the Barracuda Hunter Extreme pellet by H&N that, from now on, I will abbreviate to BHE.

When I first learned about the accuracy potential of the peculiar pellet at long ranges, I was somewhat dubitative. There was no way such a complicated pellet could be made with enough consistency and accuracy to give the precision I was hearing about.

But, I have learned along my 62+ years that there is no arguing with reality, so you have to test what seems logical, and even what seems somewhat illogical if you trust the person making the statement.
So, between that, and preparing to test the DIANA Stormrider at higher power levels, I decided to buy a tin of BHE pellets and put them through their paces.

Since the initial comments about their accuracy had come from spring-piston shooters from the Eastern side of the Atlantic, I decided to test them at the sub-12 ft-lbs level. Besides, I had been wanting to test the pre-production version of the Barracuda FT (BFT from now on) pellets which are the same weight as the BHE (at least nominally).

Upon initial testing, the BFT pellets proved to be somewhat "inefficient". Meaning that my FT rifle that yielded 11.75 ft-lbs, suddenly yielded a bit more than 10½.
Nothing to worry, a few changes in the setup and the BFT was shooting at 11 ft-lbs.on the dot, but the expected gilt-edged accuracy was not there. At the same time, the JSB Expressess were shooting at 12½ ft-lbs. So, "inefficient" is the right word.

Yes, we all know that lighter pellets will yield more energy in a spring gun and both the BHE and the BFT are 9.57 grainers (nominal weight), but properly short-stroked D54's don't have too much energy "in reserve". If you load the non-lead version of the Barracuda Match (6.6 grs). it will only yield 11.7 ft-lbs., as you can see, the "engine" has been optimized around the 7.9-8.44 grains pellets.

When I tested the BHE, almost on a whim, I got some fantastic groups at 35 yards, and not too much drop from 35 to 55. So, clearly, SOMETHING BIG was going on in here.

We have already related what was the result of shooting the 2018 Maryland State Championship with the BHE, so I will not go there again, clearly the consistency and accuracy of the pellets was there. I failed to notice some change in the gun/scope and missed the top spot for springers, but noneteless, it was a good shoot.
So, let's start with the pellets themselves:

Looking at the family of Barracuda Pellets, we see the similarities:

From left: Barracuda Match, Barracuda FT, Baracuda Hunter Extreme, and Barracuda Green.
​
Another picture in the same order:

Tells us where the main difference between the BHE and the rest of its "brethren" is: at the nose It seems to have been marked by a #0 Phillips screwdriver with rather solid sides all around except the intentionally narrow bands where the tips of the screwdriver's edges leave little material.

Running 20 pellets, lubed but otherwise straight from the tin, through the scale, we find out that they are surprisingly uniform in weight:

About twice as uniform as the BFT pellets. Do note that BHE's Extreme Spread (ES) and Standard Deviation (SD) are half of what the BFT are.

Measuring the head diameter of the same pellets, we arrive at an average head size of 4.476 mm's with an ES of 0.01 mm's and an SD of 0.003 mm's. Again consistency where it counts.
Doing the same measurements for the BFT, the head size was even more consistent 4.478 +/- 0.002 mm's, but again, the gilt edge accuracy of the BHE is not there. I have some ideas that I will discuss with H&N, hopefully, we can improve the BFT by taking some features from the BHE

From past measurements, I know that my bore is 4.48/4.50 mm's (lands/grooves) mm's and my choke tightens that to 4.47/4.49 mm's

On the left is a pellet run partially through the barrel, on the right a pellet run through the choke. You can see the difference in the indentations of the rifling's marks on the head.

We also need to correct the nominal weight. While 2/10ths of a grain may seem irrelevant, the difference is almost 10 fps on the maximal speed to be within WFTF rules (760 fps to 751 fps). With guns nowadays approaching ES's of 3 and 4 fps in 20 shots strings, it behooves the manufacturer to post and print the correct weight and not some nominal number.

We have already mentioned that the BHE pellets achieved more muzzle energy for the same cocking force than the BFT, so they are more efficient than the BFT, but not quite as efficient as other pellets, within the grand scheme of things, this might be a minor point, or it may not. We will see what this means when we reach the "Terminal Ballistics" section.

First of all, I should explain why I do not bother with "intermediate ballistics".

Intermediate ballistics is the very short section of the projectiles' trajectory where they are out of the muzzle, but still affected by the expulsion of excess propellant gases from the barrel.

In firearms, this is a huge concern, the larger the caliber of the shoulder firearm, the more concern it is because the barrels have become shorter and shorter. You may think that a barrel that is 26" long is REALLY long, but expressed in calibers, it is only 84.4 calibers long (we're talking here of 0.308" cal sniper guns). And if you go to the extreme of a Naval gun, a 22.22 yards long barrel of 16" caliber is only 50 calibers long.
Talk about pistols and it becomes even more dramatic.
Compare that to spring-piston airguns that have barrels up to 18" in 0.177" cal., those numbers make the barrel 101.6 calibers long.
Some argue that shorter barrels are more than enough to generate "Full Power" in a spring piston airgun, but those shooters are also usually limited to 12 ft-lbs. at, or near, the sea level. So, for guns designed and built with that limitation, it may be correct to use barrels as short as 10" but, in general purpose guns that can reach up to 17 ft-lbs at 8,000 FASL, then an 18" barrel is correct.
It is funny to think that some PCP's use barrels that are 135.5 calibers long, but that is a necessity of how PCP's work.

Within the realm of short for caliber firearms Intermediate Ballistics is important because the high pressure and velocity of the gases may disrupt the projectile's path and therefore reduce the accuracy, but in airguns, we can and should control this to the point of elimination.
Vortex Diverters/Air Strippers, resonant cavities, and well made reflex LDC's, all contribute to eliminate, almost at the muzzle the problem of "excess gases".

Spring piston airguns, by their very mode of functioning, require only a modest air stripper to control and eliminate the worry. We'll not be bothered here by Intermediate Ballistics.

​SO:
Having reviewed those factors that affect the pellet's life INSIDE the barrel (head diameter & weight uniformity, let's look now at what happens OUTSIDE the barrel.

In preparation for the Maryland State Championship, drop data was collected at DIFTA: 866 FASL, at 23°C, and Humidity of around 90%
​
With a 33 meters (36 yards) zero,  as you can see in the picture of the PP-Calc "Results"  screen shown below; the drops were: at 41 meters (45 yards) 3/4 mrad, at 50 meters (55 yards) 1 3/4 mrads, and at 10 meters (11 yards)  1½ mrads.
If you have never used PP-Calc, or do not understand how a ballistics solution program can calculate the BC and the rest of the ballistics solution from drop data, then go here.

As the G1 based simultaneous differential equations solved using fuzzy logic showed; shot at 736 +/- 3 fps, from a Diana 54, the pellets exhibit a particularly attractive BC: 0.242

I have to emphasize here that the much revered BC is just a figment of our imagination. A useful one, but it is just a scale number that applies ONLY to the set of conditions the test was fired under. If you want to read more about the BC, please go here.

I am sure many of you have seen other BC's listed for this pellet in a number of places, most of them poorer, but what I want to be VERY clear about here is that if ANY of the conditions change (mostly MV), the BC WILL CHANGE.
The BC is NOT an intrinsical, inherent, inimical, property of the projectile, it is just a scale factor of how the projectile behaves when fired under certain conditions.

In a way, I was expecting some great results here. As mentioned, in the first tests, there was a surprising capability of the pellets to shoot consistently to POA, to resist crosswinds, and surprisingly little drop when going from the 36 yards zero to the 55 yards line.
What was heartwarming was the consistency of the results per section of the trajectory. I always expect the BC for the long range to be higher/better than the ones for the intermediate ranges, in this case it was also true, but the fact that from 10 to 41 meters the BC's agreed so well is always a confidence builder.
It means that YOUR DATA is good.

Analyzing the wind drift was also comforting. For a wind of 5 kph (about 3 mph), the max drift at 50 meters (55 yards) was under 1 mrad.
Drift will be proportional to the wind speed once it is calculated for the REAL BC of the pellet/rifle/shooter/scope/location conditions and it will be angularly proportional to the distance, but since we think in distances and not in angles, it is best to let the app do the calculation for you.
What is important, as a shooter, is to learn how to judge accurately the wind speed.

Putting all this together, the app gives us a "reticle" (in this case, the excellent AEON DU-Line reticle) to shoot by:

So, to link External Ballistics with Terminal Ballistics:

We have a hunting pellet (Hollow Point) that is consistent in weight and dimensions.

That resists wind drift well but does so at somewhat reduced (for US hunters' purposes) power.

In my previous tests of HP pellets, I had found that the minimum impact speed for a HP pellet to expand was around 600-650 fps.
And it was terminal velocity what determined the performance, not energy.
This was true for the Crow Magnum, as well as for the Predator, the Super H Point was even more dramatic in its "need for speed".

Will the BHE pellet reach the target with enough velocity to expand and do the job properly?
If not; Will the design of the pellet compensate a deficiency in terminal velocity?

As we can see, the impact velocity at 55 yards approaches 560 fps, not a lot, and definitely not within the region where other HP pellets do expand well.

BUT, as I have said more than once: never argue with reality.

The only way to find out was to make a "Syn-daver" and test the pellets under controlled conditions and using a media I know actually replicates well the composition of muscle, bone, water and organs inside most airgun-worthy critters.

NOTE: If you are bothered by discussions related to hunting live animals, then, PLEASE, do not read the Terminal Ballistics section.

While it is generally understood that 0.177" is for feather, I generally do not hesitate taking on some furred creatures, mostly small ones, but some of them very tough ones.
Take the O'Possum, or the Badger, as examples, they are very tough and you need to know their anatomy to place the shot where there is little to no bone in the trajectory, or the animal will walk away and suffer badly. No ethical hunter wants that, and so I will say it here:

Hunting is a huge responsibility. NO pellet design, NO pellet material, NO pellet caliber can remedy a badly placed shot.
It is YOUR responsibility to know the anatomy of the animal well and it is YOUR responsibility to place the shot accurately and precisely for a quick humane kill. If you cannot assure that the shot will be a good one, DON'T shoot.
Simple as that.

A little bit of history here:
I returned to serious airgunning in 1999, that was after more than 25 years of serious firearm shooting and experimentation. I realized early on that airguns had more in common with cars than with firearms, and so I tried to approach everything with an open mind.
Along my first years of airgunning, I was helped along by true giants in the field, people like "Prof Hoff", Mike Pearson, Tom Anderson, most of them now passed from this realm, helped me understand the intricacies of airgunning. Back then, we were all helped by Edith and Tom Gaylord, that hosted the old "Airgun letter" forum.

Working together with those mentors, we came to a methodology that is repeateble, and very accurate as far as results are concerned to create a "Syn-daver"; that is a synthetic corpse that will replicate the results of the shots and allow us to take decisions of where are the limits of our equipment.

Originally, Mike Pearson liked to test the expansion of pellets into Ivory Soap bars. Why? it was cheap, consistent, and easy; and used test material was always useful around the house. But serious tests revealed that the soap was too hard and promoted expansion in pellets that would not expand in softer materials / live tissue.
Gelatin was also tried. Even when concocted to very precise specifications (Prof Hoff was a professional chemist), it would give results that would change with the weather.
Tom Anderson used to use phone books, they were plentiful and cheap (if you went to the phone offices, they had bins to recycle old ones, and it wouldn't bother any if you re-used them before recycling them (just take the lead out before taking them back to the recycling bin, LOL!) But phone books were too hard and shredded the pellets more than promoting a smooth, tissue-imitating, expansion.
So, we came to the idea of using waterlogged phone books. Soaking them overnight, making sure they had plenty of water to "drink" and then shooting at them.
But it was not perfect. The book structure made the media differ widely in the performance given the shot placement.
Next idea was to create something different along the lines of the waterlogged phone books and we thought of using newsprint. Now, newsprint is a special type of paper. It has good tensile strength and a good "Mullen" (resistance to perforation). It is easy to get, and you do not really care if it is wood derived or sugarcane derived, it has to meet the criteria laid down by the rotary printing presses that use it (multi-million dollar machines). So it has good quality control.
Making "blocks" of squares of 8"x 8" putting the blocks in ZipLoc's and then soaking them overnight resulted in an excellent test media.
The fibers did abrade the pellet as would muscle fibers, and the density of water-soaked paper pulp pretty much approached what is found in live tissue.
Heavy duty Zip-Locs also imitated rather well the consistency of skin.
It had one added advantage: you could insert bones to see what would happen if the pellet hit a bone (whether intentionally or not).

It had ONE disadvantage: it did not replicate the effect of shooting through heavy feathers, but knowing that, you simply had to take your shot from an advantageous position when doing the real thing.

Nowadays, newsprint is used mostly to package things. As newspapers have reduced their circulation, you can still get newsprint as packaging paper or children's drawing rolls.

The tests you will see below were made using this methodology. I will not post pictures of the bones used but will tell you that they were domestic chicken. Neck, shoulder, and wing bones.
The whole was packaged into a large, heavy duty Zip Loc and the location of the bones was marked.
Also, incidence angles were used to ensure that the results were as true to life as possible.
Shots were taken from 50 meters (55 yards).

We shot 5 pellets into this "test subject". Going from the softest "from the bottom" shot (no bones) to the direct-bone splitting neck shot, and these are the end results:

To the left is an unfired pellet, to the right is the "case study" for each shot. Going from soft to hard targets, from left to right.
​Looking at them individually:

Thinking in real terms about this performance is not easy, probably the best way to rationalize it is that the least expansion still produced a 0.20" cal hole, while the greatest expansion produced a 0.22" cal. hole.
Since pellets cannot kill through hydrostatic shock (and it is debatable that most CF rounds do), but kill through tissue destruction, it is clear that if you would not hesitate to shoot a turkey in the neck with a 0.22" cal. domed, solid, pellet (where legal, of course), you might consider this pellet.
Of course, shots need to be kept to the range where you can place the shot within ¼" of POA. Whatever that distance is, is up to you to test yourself and find out; and then limit yourself to that range.

​The terminal velocity curve tells us that shot at this slow speed, you should expect expansion at 34-35 yards. But reality has proven different. In this sense, it is the design and the hardness of the pellet what makes it a good performer. Could pellets be made of softer lead to have even better expansion performance?
According to H&N, no. The hardness of the pellet is mostly determined by the mechanical requirements imposed on the pellet as it is extracted from the dies.

What would happen at higher power levels? It needs to be tested. It could go both ways.

Part of the quandary is finding out WHY the design works so well at such slow MV's.
And doing tests at higher powers is definitely within our capabilities and objectives, but it will have to wait.
As I said above, there are ideas that need further discussing with H&N.

​​The situation reminded me of an experience, long time ago (1972), when I was looking for a bullet that would be a real hunting bullet, but shoot right alongside the "Match" bullets in my Steyr SSG 7.62X51 NATO. I looked at most designs, tested quite a few of them, from West of the Atlantic: Nosler Partition, Speer Grand Slam, Sierra MatchKing and GameKing, Hornady. But nothing really quite make the cut, back then the concept of using precision jackets and swaging your own bullets was not that common, or understood. Though I would end up heading in that direction.

Then a friend from RWS (before it was bought by UMAREX), offered to send me some Brenneke "TUG" bullets from the East side of the Atlantic. After all the formalities of the case (and there were a LOT), when they arrived and I tested them, I was very pleasantly surprised.

"TUG" stands for Torpedo Universal Geschoss (or Torpedo Universal Bullet), it is a bullet that has  dual core, and a complex profile of different diameters and bands that ensure not only its performance on the internal ballistics (pressure and heat in barrel), and on the external (trajectory, accuracy, and hole-cutting) ballistics side, but also on the terminal ballistics side.

After sectioning a bullet and testing somewhat extensively, I was able to replicate some of its characteristics by using a lengthy and complicated process that involved casting two cores (different hardness), then using three different punches to swage the cores, weld one of them to the jacket, then using a rebated boat-tail base forming die and then using a dual diameter nose forming die to finish the bullet with a point forming die. It took about 10 hours to make 50 bullets.

But they shot like a dream, and their performance in game was simply outstanding.

I owe much of my understanding of internal, external and terminal ballistics to the inventions of Herr Wilhelm Brenneke.

​Back to airguns: in essence, H&N has made a hollow-point pellet, that behaves, for all intents and purposes, like the domed ones.

It flies like a 0.177" and hits like a 0.22"

It is accurate, consistent, and has a good BC.

¿What else can you ask for?

If you have a chance, test this pellet in YOUR rifle, make sure you start at low MV's (I would recommend 730-740 fps), and then up the game till you find what is the limit of the pellet in YOUR barrel.

¿Am I going to do that?
​
Not for the time being. I need a pellet to shoot FT matches and while 10 fps more might be important., when travelling 500 to 10,000 miles to Matches, it is more important to still be "legal" when you get there; and ½ ft-lb is a somewhat narrow "protection buffer". I feel comfortable that I will not exceed the "legal ME" but I don't want to push my luck.

Hope you have enjoyed the read of such a long article, but I really do think that this pellet is a door opener and, hopefully, we can get some ideas past the threshold of that door.

Keep well and shoot straight!



​HM

DISCLAIMER, I will post the same disclaimer as I used in the original post about swapping triggers in the LGU:

1.- Swapping the trigger blades WILL invalidate the warranty of your rifle.
2.- ANY user intervention in the trigger MAY result in an UNSAFE condition. Once you get into the trigger you are on your own.
3.- I have no control of YOUR actions, so I can take NO responsibility for the results YOU get. This process proved safe and sound in THIS gun. I cannot guarantee that it will be the same in YOURS.

Having said that, let's dive into it:

In the past years, I have had the opportunity to tune and shoot a number of LGV's and LGU's, and I still like the guns. They are not the ideal gun for me (though the LGV seems to be a better match), but as we have discussed in the past, we are all different and some guns will shoot very well in some people's hands while shooting horribly in someone else's hands.

Among the most important characteristic of a gun that is to shoot accurately many times in a day, is the trigger. For most shooters, the Walther "Match Abzug", or the "Yankee Tune" trigger solutions will be all they ever need, or want.
I have installed a few of the "super-custom" triggers (like the BMS's and the RE's), but there was always something that didn't really "jive" for me; perhaps I am spoiled by my DIANA T-06's. But, as we just said: we are all different. And so, when a friend asked me to add a Rowan Engineering trigger to his LGU and document the process, I decided to put this blog entry together.

Experiences with Rowan have been somewhat less than stellar.
As an example:
When I ordered this last trigger through the website, everything seemed to be straightforward, when I received an Email from them supposedly enclosing the tracking number, but without any number at all, I suspected that there would be other problems.
So, after writing to them and receiving the proper tracking number, I followed the shipment almost daily.
When suddenly the USPS sent me an alert (I have a USPS account and had registered to receive updates on the package), about the "item being returned to sender because it is undeliverable", I jumped into action and went looking for the package to my local Zip-Code head office, sure enough, after 90 minutes of waiting and repeating the same story several times, someone took pity on me (actually the Germantown, MD, USA, PostMaster), and personally went to look for the parcel.

When I received it, I understood the whole ("Undeliverable")  thing:​

Tell me in all honesty ¿Would you have been able to deliver such a package? I wouldn't.
An Email to them relaying the same picture included above produced the following response:

"Hello Hector,
 
I have found out what happened with the address.
 
Occasionally the printed address is missing some detail that is hand written afterwards.
To stop this smudging , clear tape is added over which we have been doing for several years.
 
It appears now that the last batch of print consumables is different or the the clear tape has changed in someway and now over a day or so causes the printed ink underneath to erase !!!
Very strange.
 
Anyhow, we will not add the clear tape from now onwards.
 
Best regards,
Derek Rose."

By the end of the day, I only lost 3 hours hunting down the package but now I had it in hand.
​
Anyway, back to gunsmithing:
This is what you get in the envelope:

And when you unpack it, this is what is inside:

You will also get a black and white printed version of the instruction booklet:
http://rowanengineering.com/pdf/WalterLGVLGUAdjTriggerInstruct.pdf
One of the things that strikes any observant gunsmith is that the adjustment screws (as the trigger is shipped) are even further apart than the ones in Walther's "Match Abzug"

If we do the same comparison with the BMS trigger:

So, how can it accomplish a lower trigger pull with screws that are even farther apart than the OEM triggers?
Reality is, that as it is shipped, it can't FOR THE SAME SET OF CIRCUMSTANCES.
You can read carefully, again, and again, and AGAIN, the instruction sheet included, there is no mention of further adjustability.

But if you look closely, you can see that there is a third hole in there. And it is tapped for the same screws. So, if what you REALLY want is the lightest trigger pull possible without any further work, then you need to change the rear screw's location from the outside to the center.
But, in a sense, we are getting ahead of ourselves because when I installed the RE's trigger in THIS Walther, then the piston would not make the trigger latch onto the stem.
I looked and looked and looked and could not find what the problem was, until I looked closely at the safety. It would not move to the safe position.

Upon close examination, it was determined that there was not enough space between the housing, the safety pawl and the new trigger blade for the pawl to enter into the cavity of the trigger.

My first reaction was to shim it a little, believing that the problem MUST be a minor one, a question of one or two thousandths of an inch.

I measured the thin washers in the trigger mechanism and made some of copper shim material of the same thickness:

Yes, I know they are not as elegant, but they fit and didn't snag on anything, so I tried one on the offending side. 
NO luck.
Tried two
NO luck
Tried three
Finally, the pawl could enter the trigger's cavity.
BUT, when I assembled the trigger, it was clearly wrong. Once assembled the housing put enough pressure onto the washers as to lock the parts (sear and blade).
So, what was there to do?

I remembered then that when discussing the trigger with the designer, we had talked about Zinc parts.
Few people really understand why, but those that have worked in precision moulding know that moulds that are made to mould zinc have a relatively short life. It's not that they get clogged, or they break, or they loose their definition, it's that they GROW on the inside. So, parts that are moulded become increasingly thick. A friend once told me that molten zinc dissolved iron/steel; and that is possible, as crucibles for melting zinc are usually ceramic, but I do not know this to be absolutely true, though I think it makes sense.

Not a problem when you know the tolerances and you can plan ahead and leave room for parts that may have up to 0.015" of extra room here and there, but when you design an aftermarket part you run the risk of not being able to use that part if the manufacturer has a little more tolerance built into its designs.
And so, the solution was to thin out the pawl a little, but it is a small part.

Well, part of the reason why early gunsmiths were also clock makers (Girandoni to name just one), was because we develop the tools and the eye to work to very small dimensions by hand.
​
​The small vice was taken out of storage and put to good use:

Once the offending 0.027" were taken off using needle files, the pawl entered smoothly into the trigger blade cavity when the piston's flat part of the latching button hit the safety extension lever:

​What is important here is the DIFFERENCE between the two screws HEIGHTS. Since the "watertables" of both trigger blades are not the same, we cannot ensure that the heights should be the same, but we CAN say that the difference in screw heights should be the same so, we took the height of the front trigger screw and added 0.95 mm's to the second height, and we used that as our starting point.
And, sure enough, the trigger pull changed little.
I then adjusted to the lowest possible weight and measured an average of 5 shots.
It was interesting to note that compared to the "Yankee Tune​", the difference was almost non measureable.
To take the experiment further, I moved the screw to the closer position (more forward), and re-tuned the trigger to the lowest possible weight that I still felt was "safe". It was then that we could observe some appreciable differences.

Here we need to add that adjusting the RE's trigger is not as easy as it should be, every time the screws need to be adjusted, the blade itself needs to be moved/removed. 
By the end of the day, the RE trigger was set to 17 oz. (close enough to 1# even) and the job was considered finished.

One important aspect is that if you need to work on your gun, remember to remove the trigger blade, as the trigger guard will not release the trigger with the blade on. 
You can modify your trigger guard to create room, but in general I do not advocate modifying structural parts and the trigger guard is an important part in the bedding of the LGU and LGV. They are not as "tunable" as DIANA mod. 34's using the rear stock to action screws, but a properly set and consistent trigger guard torque is important to achieve utmost accuracy in any gun.

Since I already had the trigger pull scale out and I had the rifle vise pointed at the pellet trap and everything was set, I decided to measure the trigger pull in my personal LGV (shooting at 16 ft-lbs in 0.177"), the average of 5 trigger pulls was 15.6 oz.
Sure enough, my LGV has stoned trigger parts and uses the "Walther Match Abzug".
Further, the trigger on the LGV feels "crisper" because once the force of the opposing sear spring has been overcome, the trigger pull is finished in a VERY SHORT DISTANCE. Whereas the BMS and the RE triggers need a longer distance to actually release the shot.
Nothing new or out of the ordinary here, it's a simple result of levers and fulcrum points. Longer lever, more force, but shorter distance. Shorter lever, less force needed, but a longer travel is required.

In here I would like to insert RE's response to the question of when the third screw hole had been added:

Hello Hector,
 
The additional tapped hole was added in the last few months, we’ve been producing the trigger for several years.
We often make incremental changes to our products and this was a result of one or two comments I have read on various forums that people have done themselves.
Like almost all manufactures, we don’t offer “upgrades” to the latest version during the product life cycle.
I’m not entirely convinced that the extra hole it is necessary or even gives an overall improvement, but was added so that customers who wished could experiment.
I find that although the new grub screw position will reduce the pull weight, it also increases the trigger creep which is very undesirable.
 
Our recommendation is to position the grub screws in the original intended position.
 
Best regards,
Derek Rose.

Couldn't have said it better myself! LOL!

​Which trigger is the best?  All of them, or none, it all depends. Remember we are all different, and depending on your habits and customs as related to shooting, one trigger may be better for you than the others.
An undisputable advantage of these "supercustom" triggers is that you can move the blade itself back and forth, and twist it a little, if that works better for you, the Match Abzug, or the OEM triggers do not have this facility.
A good gunsmith can set the release point to a reasonably wide latitude of positions forward and back, but moving the trigger blade itself makes more sense for the home tinkerer.

The BMS trigger does have more adjustability in the LENGTH of the first stage because the safety pawl to trigger relation is less demanding than in the RE's trigger.

That is part of the beauty of gunsmithing, there is so much variety!

Anyway, hope this short note helps you identify which trigger is better for you and why, and also may or may not save you some money because at around US$80 for the RE and US$140 for the BMS, getting some polishing stones and a longer M3 screw; or asking a friend to do it may make more sense.

Keep well and shoot straight!

Since no one, (until today, RR did) had expressed any interest in the higher power regions for this little carbine, I took the time and indulged one of my personal projects:
¿How would this little carbine fare as a youth oriented 3P Airgun "SPORTER Rifle"?

¿Why do I think this is so important?

Of all the shooting sports currently in practice, none is growing as fast as the Sporter section of the 3P Airgun.
Sponsored by a Council that includes the CMP, the Army Marksmanship Unit, the Marine Corps, Navy and Air Force. There are other civilian sponsors: 4H Clubs, Daisy, and Orion.

The Council reviews the rules and enacts them, but the rules have been pretty much stable for several years now, unlike some other airgun sports.
The Council also saw the importance of initiating the shooters under a "Sporter" Class, that is a severely limited class of rifles and so, it has all the makings of a practical shooting discipline for all.

Everyone that knows and/or has shot with me knows that I like most those disciplines that teach as much as possible, the practical elements of good riflery. They are skills that once acquired will remain with you for the rest of your life and will yield great satisfactions.

Once those basic skills are learned you can choose to go into a number of specialized disciplines with great success. Trying to jump into the deep of the pool without acquiring first good habits may create a lot more vices than virtues.

I firmly believe that we need to put more emphasis on teaching our youth to shoot, without young shooters, shooting itself will become an endangered sport.

And so, with that in mind, I set out to research what the Stormrider could do when tuned down to sub-600 fps as the rules call for.

I will not bore you with endless strings of shots nor the two tries that I had to make to get to the objective MV, two tries that took all of 15 minutes.

What I will tell you is that after the final configuration for the TP of this very limited power discipline was finalized, the shot count had gone from 50 to 90 shots per fill, MV's were 570 fps with JSB S-100 pellets and 530 with RWS SuperMag. Variations on the MV's were very low (under 1%) for the shot strings and so, consistency was there.
It's been many years since I have not had to test all the different head diameters of the Finale Match, or he R-10's, and so those two were the only two WC's I had on hand.
As the saying goes, the proof of the pudding is in the eating, and so I shot a few groups to ascertain what sort of accuracy/precision one could expect from the pellets and the clear winner (between these two pellets ONLY), was the JSB S-100 

Here you can see in the top left hand bullseye what a 10 shot group at 10 meters looks like

The bottom Bullseye is a solid "10", not perfect, not 10.9, but still a very good "10"

The group of 5 bullseyes on the right is an exercise, resting elbows on a stool and sitting on the floor.
Some good shots, some others not so good, but is, eminently, a "Very Shootable Carbine", for me to shoot a 90/100 at these targets is quite a good result.

And to finish off the test, but this time, completely offhand:

Apart from those two occasions where I used the wrong aimpoint in the scope's reticle, all shots landed exactly where I was pointing the gun at the moment of trigger release.

As I said, it is an eminently shootable carbine.

To finalize the test, it took 45 pump strokes from my Hill handpump to refill the air tube.

2 shots per pump stroke ain't bad.  ;-)

There are several modifications that will need to be made to fully qualify within the rules, and further refinements could be achieved with a larger assortment of pellets to test, but the capabilities of the machine are there, and that is always a good starting point!

Keep well and shoot straight!






​HM

Well over a year ago, when Tobias Schmidt and I met at the Pyramyd Air Cup 2016, we had a good conversation.
Among the things we discussed was the idea of expanding DIANA's offerings to the shooters by using OPP's (Other People's Products).
While that did not make me very happy, I understood the need of the company to SURVIVE to then THRIVE (and we will go into that in another blog entry). It was a need mandated by the conditions under which GSG acquired DIANA, and the modern, virtually borderless world we live in.

As time passed and the specifics became known, there was one particular element that intrigued me no end; a small PCP carbine that is marketed around the world under different brands: Artemis, SPA, and others I surely do not know and cannot even pronounce.
DIANA decided to market this small carbine under the name "Stormrider", so as soon as Air Venturi / Pyramyd Air had them in stock I ordered one.

Around that time, Tobias and I met again at the Pyramyd Air Cup 2017 and even more interesting conversations ensued. Nothing firm, but a willingness to work together and the idea of a visit to Ense, to get to know the people there and have some technical conversations. The date was set and a couple of weeks before the trip, my first Stormrider arrived at the workshop and I proceeded to a full analysis and disassembly.

Before we progress any further. my legal counsel again has the floor and he says:
The modifications and operations performed in these tests, and described in this article, were safe for the gun in question. No warranty is given nor implied that these modifications will work or are even safe in other guns of the same style, marketed under different brands.
Working with High Pressure Air has its own risks. If the reader is not fully cognizant and familiar with these, he/she should have the work performed by an established and reputable professional.

OK, so we're done with that! LOL!

Another thing that should be stated categorically is that DIANA's intention, from the "Head Honcho" down to the rest of the Team is that guns marketed under the DIANA brand WILL be as good as can be had OoTB within their class and market niche.

So, let us start then, and I would like to state unequivocally what the Stormrider is NOT:

A Stormrider is definitely not a P-1000 (which, BTW is now on its second generation as the "EVO 2" improved model.

If you want a gun that gives you 50 shots at 22 ft-lbs, even when shot in quick succession using a magazine, get a P-1000. They are great guns, difficult to work in and difficult to "tame", but they are great guns, powerful and accurate and they have a ton of shots with their 4,500 PSI /300 BAR's tanks.

The Stormrider is a completely different beastie.
While some have said that it is a "little" carbine,  I do not fully agree, the reality is that is has a full size LOP:

At 14 3/4" it is hardly a kid-sized airgun.
And the distance between the rear of the pistol grip and the trigger, are not for a 10 year old's hands.
If you have considered the Stormrider as good youth/petite's carbine, just be aware that you may have to trim the stock to fit the shorter LOP's needed by those smaller shooters. And that they will have to learn their trigger hand hold and trigger squeeze/release accordingly. It is, though, a svelte lady, and definitely not a rifle, so let's think of it as a carbine.

We will not delve into the OoTB behaviour, that has been researched and reviewed enough in the excellent Hard Air Magazine , in Pyramyd's "Insyder" as well as their sponsored blog, and in several other Video reviews, just go to YouTube.

What surprises me is that in ALL reviews, the main "selling" point of the carbine is its price.

Well, surprise! I am going to go against almost everyone else and tell you that the great attraction of this little carbine is its POTENTIAL.

Yes, to make an analogy that will surely date me as an "old geezer", LOL!, I will say that it is like buying a simple Chevy Malibu (or Dart. or Mustang) and turning it into a small but extremely interesting race car.

Let's start with

The Trigger

One of the common main comments/complaints  is that the trigger is not adjustable. Well, I have to disagree. The trigger may not be EXTERNALLY adjustable, but inside there is . . . you guessed it, potential!

First of all any half baked gunsmith can stone/polish the sear. Yes it is a lengthy process if you want to do it right. But you can do it without any sophisticated tools. You can use wet-or-dry paper laid on a piece of thick plate glass and progressively use grits: 380, 400, 600, 800, 1,000, and 1,200 with water. If you want to get it really well done, then a sliver of black hard Arkansas whetstone (which you should have if you are a hunter because nothing gives a better edge to skinning knives than black hard Arkansas whetstones) can give the sear the ultimate polish.
Avoid using a Dremel because you do NOT want to change the angle or the flatness of the sear. 

You should end up with something that looks like the above piece.

Next comes the trigger blade:

Yes, there is a screw in there, and where there is a screw there is some adjustability.

A home tinkerer can simply adjust this screw that regulates the engagement of the sear into the hammer and can turn the trigger from a lengthy and/or gritty experience to the proverbial "breaking glass rod" of a trigger that is conducive to good shooting.

A professional gunsmith will reverse the direction of insertion, use a stubby allen wrench (1.5 mm's), change the screw and use either a rounded/polished face screw, or a cone point.
​If the polishing of the sear was well done, the cone point offers a degree of repeatability that the rounded face screw does not. But only if the polishing phase has been done properly.

 On the left is the OEM screw, on the right is a cone point screw.

If properly done, the trigger can be as light as a fraction of a lb.

AGAIN: ALWAYS MAKE SURE YOUR GUN IS SAFE! Submit the gun to the bump test: dropping it butt down from 12" height and it should NOT fire. If it does, readjust and repeat.

The trigger will be a single stage trigger, there is no way around that, though we are working with DIANA on a new design that will be a true double stage trigger.

Of course, do not forget to Loc-Tite your setting!

For a modicum of effort and very little cost you will have a trigger that breaks cleanly and consistently, and depending on how well you did your job, it can also be very light and still safe.

A note here: NEVER use lubricants between sear parts. It will provide an inconsistent release that will be thermally sensitive and what is safe in temperate/cold weather may become completely unsafe in hot weather. Let the hardness of the metal injection molded parts and your polishing do the friction reduction.

Now. let's go the next area:

The powerplant in 0.177" cal.

In general, I would say that the 0.177" cal. is a target/plinking/expert hunting caliber. You need to be a good shot to take any major prey with the smallest normally available caliber. Head shots, long stalks/short ranges, and good field craft are essential to being a successful hunter with a 0.177" cal. rifle It IS doable. Lots of our cousins across the pond do it day in/day out. But it does need a well practiced, ethically minded, and precision/accuracy oriented hunter.
Yes, the gun can yield around 20 ft-lbs in 0.177" cal. Yes it can be done, and if there is enough interest (hint: if you want it, ask for it in the comments section) we'll go there, but the OEM architecture of the gun has its greatest  . . . potential!  ;-)  at around 12 ft-lbs.
Another aspect is that there is a ton of literature, data, serious experiments, and documentation at this power level. I would say that thanks to the FT shooters, no pellets are better understood than the JSB's Exacts in their Express (7.89 grs)  and Mid Weight (8.44grs.) versions.
Experience has shown time and again that they yield VERY LITTLE in terms of BC and the gain in MV is more than enough to achieve great results with these pellets, even at longish (55 yards) distances.
Of course, it also helps that Predator's PolyMag's in 8 grs. are extremely accurate out to 45-55 yards, usually shoot well in those barrels where the JSB's shoot well, and give the GOOD hunter an extra edge of surety.

So, having explained the reasons to choose this power level, let's think out loud what is the main area of opportunity for improvement.

In my honest opinion, the single greatest area of opportunity is the shot count and consistency.
There seems to be a common denominator between reviewers to resign themselves to work with the 12-20 shot count that a relatively large and steep power curve gives, this is as much an effect of the manufacturing (and therefore a big factor in the low cost of these guns) as it is an effect of the "GAMarketing" practices of trying to sell a gun on the sheer MV or ME.
Using the SAME spring  and hammer for ALL calibers has to be an extremely rough compromise. And yet that is what is done. I repeat that it is one of the factors that allows this gun to sell for under $200 retail, but technically speaking it is a HUGE compromise.

Now, to be quite frank, not everyone has the time, knowledge, nor energy (you need to refill the gun quite a lot of times if you want) to tune it the hard way (balancing the hammer weight, the stroke, the spring and the valve face). Yes it can be done, but it is not an hour's job.
So, my conclusion was that the best way to serve the shooters would be to get a good regulator for these guns.
There are already some regulators in the market for the "Generic" form of the DIANA Stormrider, but some of them are expensive (€ 89,00), some of them require the user to make some modifications to the gun, and some are not easy to de-install, should the case arrive where the user decided he was going to go the hard way.
After some research, and based on previous experiences with HPA equipment, I decided to work with ALTAROS Air Solutions to develop not one, but TWO regulators for these carbines.
Why TWO? One of them needed to be "absolute" (non-vented) regulator, it had to be user installable, without ANY modifications to the gun (as that is completely illegal in some countries), and it had to be easily de-installable.
The other was a more specialized unit that was to be installed by a licensed/certified gunsmith, and it was to be vented.
Vented regulators are more thermally stable, but they are more vulnerable in extremely dusty environments and need to be installed by a competent gunsmith because not only do they require the removal of all the internals of the gun, they also require extreme care in keeping the vent operational when assembling the gun back.

By the time DIANA's invitation to Ense came, my carbine was on its way to the Czech Republic and I already knew exactly what I wanted.

Here I have to commend the diligence, patience, and knowledge of the Altaros people. They listened, and we had some strong and energetic discussions, but the technical know-how and the needs of the shooters prevailed and the end product is more than satisfactory. Working with them was an honor and a privilege.

This is how the regulator looks like when delivered: 

There is an insertion tool (that also works as an extraction tool), and an adjustment tool. The regulator itself and some spare ORings.

You will need to start from an empty air tube, so either degas it, or shoot it till it is empty. Once the air tube is empty, you can start the installation:

Three screws link the Stormrider's action to the stock, do note they are ALL different. Do NOT get them mixed up.
Once those screws are removed, you can take the action out of the stock.

Do note how the manometer is housed in a sleeve that is then screwed into a "manometer block" inside the air tube. This manometer block also acts as a de-pinger, you can see the inside of the air tube here:

A look at the train of parts would be like this:

And a detailed look at the manometer block is here:

Now, I am showing you this because you do NOT need to disassemble the carbine. The regulator is inserted when all the parts are already inside the rifle. As a matter of fact, you could install the regulator without taking the action out of the stock.
​
You simply remove the end cap of the air tube (CAUTION: MAKE SURE THE AIR TUBE IS EMPTY!!!!):

You assemble the regulator with its insertion tool:

By screwing in the insertion tool into the front end of the regulator:

Lube the regulator's ORings with a QUALITY ORing lube, and then insert the regulator till it stops against the manometer block.

Here I must make a note:
We've had reports of earlier models of this gun that do NOT have the manometer sleeve and the manometer is screwed directly into the air tube/block.
​
IT IS NOT SAFE IN THESE RIFLES TO USE THESE REGULATORS!
As long as it is a DIANA airgun, it WILL have the manometer block and the manometer sleeve. We tested this arrangement to 300 BAR"s and it proved safe, but it is an arrangement that we cannot guarantee as safe in any gun that does not have these parts. It is up to the shooter to ensure that HIS/HER gun is safe for this conversion.

Once you install the regulator, simply cap the air tube and air-up your gun.
For these tests I used a Hill Hand Pump because I wanted to make sure that users did not NEED a compressor, or an air tank to benefit form this mod:

The technique to use a pump when starting from ZERO pressure is simple:
Give the pump 20 QUICK strokes and ensure that the ORings have been "set".

Then you can start the REAL pumping.
Just in case someone is not aware of this, the proper technique to use a hand pump at high pressures is to "dwell" a littte at the bottom of the stroke.
I drop my full weight (all of my 168 lbs) on the pump handle and count slowly "one", and then raise the handle, then repeat.
The Storm Rider takes 100 more pump strokes (apart from the 20 used to set the ORings) to go from 0 to 220 BAR's.
Once everything is working, it takes just 45 pump strokes to go from 100 to 220 BAR's

By now, I am sure someone is calling me crazy. Why would I pump a gun up to 220 Bar's when it is clearly marked 20 MPa (200 Bar's) max?
Well, on one hand because it is perfectly logical, productive and safe now.

One of the aspects of that huge technical compromise that comes from using the same parts for all caliber guns is that you cannot risk a valve lock. Pumping/filling to more than 200 BAR's is just tempting fate. A valve locked PCP is a grenade just waiting for the next dumb person to pull the pin. That would not be good and so it is to be avoided, but now that we have a regulator, we can pump it JUST above and be perfectly safe.
The 220 BAR's fill point is within the capabilities of the excellent Altaros regulator and it gives a good boost to the shot count and performance of the gun that would be otherwise impossible.

The overall process of opening the air tube, inserting the regulator and refilling the gun takes all of 47 minutes, and that is taking photos along the way, I am sure that it is "quick work" for someone not in the habit of making blog posts, LOL!

But, what have we gained for our investment and our time?

The short answer is that we have gone from "12 - 20 usable shots" (16 in our case) :

To 35 usable shots:

Do note that the extreme spread in the "as issued" case was 33 fps and in the "Regged ONLY" case was 27.
So we're trying to compare similar situations. The eagle eyed among you will note that in the "as issued" case the gun was a "20 ft-lbs gun" so, yes the gun was delivering more power, but what is so important about power when you have such a wide variance of MV's, the pellets are not flying at their maximum stability speed and above all, when your machine is being totally inefficient????
​
Airgunners pride themselves in the ability of their airguns to hit small targets at the needed distances with sufficient efficiency, consistency, precision and accuracy for a good hit. Whether that means a clean kill or a downed target, or a perforated bottom of  small can is irrelevant.

But, like they say on TV: "WAIT there is more!" ROFL!

I said that the machine was inefficient. And if you REALLY want to explore the limits of the efficiency of such a small machine, you will have to work with it the hard and long way, but there is a shortcut:

You can "choke" the machine at the point where it is starting to be inefficient and render it more efficient.

How?

Simple! Tailor the Transfer Port to the needs of the pellet.
​
¿THE PELLET?  What is this guy talking about? We're talking about the rifle!  ¿no?

;-)

Yes, but at the very instant of releasing the air blast into the barrel, the pellet is the last "valve" in the system, and therefore a combination of the pellet's weight, hardness and head & skirt diameters will determine what is the "release pressure", thereby effecting an impact on the overall efficiency of the system.

Because PCP's tend to be more efficient with the heavier pellets. I chose to optimize the TP to the 8.44 grs. JSB. and so, after some fiddling with successive numbered drills. I found what I wanted: the smallest TP that will deliver the desired energy, in this case something reasonably close to 12 ft-lbs, and this is the result:

Yup! 52 (FIFTY TWO) perfectly usable shots between 220 Bar's and 100 Bar's

Good enough for a medium FT match, or a good 3X10 run, or a good night at the stables getting rats. Pigeons in barns and stables need a different approach, and we'll get to that later, when we explore the 0.25" cal.

Do note that we do use "full ballistics data", we do NOT exclude those shots that are questionable, like shots #39 and # 41

Because the "fiddling with the TP" does NOT require "deflating" the gun, I think it is within the realm of most shooters to do.

Are there other ways to improve on the efficiency?  Yes! the main one would be to play with the hammer weight and the spring force. But that takes time and knowledge.

Are there ways to have a gun that is regulated and still puts out 17-18 ft-lbs?  Yes! We started with a "low side" pressure of 100 BAR's. Adjusting the regulator up will also move the speed up. Why would I stop at 18 ft-lbs?  because pellets are not stable much above 875 fps and if you do the maths, that is the speed at which the 10.5 grs / 0.177"cal. pellets reach that energy.

Again, if there is interest, we can come back to this point and explore other "regions of operation".

For those that are graphically oriented, here is a chart showing the comparative charts:

Do note that the lowest MV shown is 700 fps in the vertical axis.

And just to finish off this section, let me tell you what was the TOTAL DELIVERED ENERGY for each case:

As issued, the gun delivered over the 16 shots 323 ft-lbs.
Regged, the total energy delivered was 480 ft-lbs
Regged and Optimized for 8.44, the total energy delivered was 636 ft-lbs

So in return for your good 45 pump strokes, you get much more when using a regulator and an optimized TP.

Many times we have discussed that MV is not everything, sure it needs to be delivered inside an accurate barrel, but in this case I would say that other reviewers have established that these guns are accurate as they come, regulating them can only help. And that while consistency and stability is not a SUFFICIENT condition for precision and accuracy, it is indeed a NECESSARY one.

If there is interest, we will explore other aspects in different calibers.

Hope you enjoyed the read, keep well and shoot straight!

HM

As is normal for this time of year, there are conversations in the fora, facebook and in the airgun chat rooms about what is the behaviour of Spring-Piston airguns in cold weather.

And with winter temperatures getting more and more extreme (CNN reported 150 million US Citizens under Wind Chill alert for 2018 New Years Eve and record lows expected in 27 locations, with further 24 record-breaking lows for today -Tuesday-), I think it is normal to start thinking about the long term future of the winter hunt or FT Match and how to prepare for it.
Some may say that the solution is a PCP, but that is not quite right. Filling procedures need to be different in Sub-Freezing temperatures than in warmer conditions, and the lubing of the hammer/action also needs some attention. Shot count may or may not be affected, it depends on how your regulator works (or not) at sub-freezing temps.

Sadly, there is a lot of misinformation out there, from some manufacturers claiming that their (insert the name here -Nitro Piston / Re-Axis / Gas Piston / NP2 / Vortex Gas Spring, etc.- ) are not affected at all by cold weather, to those "experts" that perform tests with large freezers and/or in cold cities (there are about 14 cities in the US and their urban areas with populations in excess of 1 million that statistically have more than 100 freezing days in a year, and the list is growing), that show decreases in performance of between 8 and 13%

RANT WARNING!
IMHO:
Some of those videos perform what I would call "Scientific Murder".- invoking one bit of science to explain everything that is going inside a cold airgun, most of them use the Gay - Lussac Gas Law, which a particularization of the Ideal Gas Law.
In their minds, the pressure in a vessel that is dependent on the temperature once a specific volume of gas has been sealed in, is the all-explaining, all-encompassing law of physics that explains the decrease in performance of some airguns (those tested).
And the fact that the reduction in MV coincides numerically with the calculation of the loss of pressure is the proof-positive that all gas springs HAVE to suffer the same reduction in output.

Problems are:
1.- The Gay-Lussac Law in essence is just a manifestation of the Law of Conservation of Energy, therefore MV has nothing to do with energy unless we understand that there is a quadratic relation between them
2.- There are other aspects besides the "spring force" that determine the output of a gun. Some guns are more efficient than others, some are less. From seal sizing and hardening with cold, to lube thickening/sticking, to lead hardness, to air density, and others, the "Force" of the spring is definitely not the only quantity that matters.

The OSS (Over Simplification Syndrome) is a common human trait. We generalize the bad things that happen in our life and attribute it to one single cause of our choosing (from the specific "god of ---", to "those blooming inmigrants", to "those -expletive-  -religious group-") without stopping to think that perhaps our problems are more complicated than the one-dimensional life we imagine.
It is so common, in fact, that it's one of the preferred tools of tyrants to control a population: Drive down the educational standard, turn them all into simpletons, then control them through their fear of -mostly imaginary-  enemies.

RANT OVER

So, let's look in detail at what can happen when one gun is prepared, from the beginning, to be as stable as possible under all environmental conditions.
Granted that this is another one of those "ONE GUN" experiments, but in this particular instance what was done to the gun is a KNOWN quantity, whereas in the cases I've ranted about above, the specific condition of the specific test gun is a complete unknown.

An important factor here is to define what is "cold".

When we landed in South Connecticut some years ago, we took it for granted that winters with temps in the 258° K ( about 5° F) would be normal winter temps. Then we started noticing the temps in Minneapolis, Chicago, Minnesota, Milwaukee, Rochester, etc.), and realized that there were much colder places.
What has changed in fairly recent years is the deepening of the "Polar Vortex" that has driven the winter temperatures in the EAST of the US to record lows year in and year out.
Then we moved to Maryland and I hoped I would not have to shovel the usual 9 ft of snow and that the winters would be less harsh. Well, so far at least, one of the hopes is true. No shoveling till today, but temps in the 260° K (about 8° F), belie the fact that summers here will reach 303 °K (about 86 °F) with over  93% humidity.

So, the tests I am going to describe were done in Maryland, are valid for the gun tested (a 0.20" cal D34 converted to N-Tec) and are not intended to be a "universal description" of what can be expected from the run of the mill, OEM issued, airgun equipped with a gas piston of any name.

The test setup was quite simple:

​A rifle, a chrono that was kept indoors till the time to test was at hand, the rifle's preferred pellets and a pellet trap. Nothing complicated.
Do note however, that I am using the infrared lit screens. At least THIS chrono operates with infrared light. And trusting the infrared (heat) emission of a cold sky is inviting disaster in a test.

What is different here is the gun itself.
It started life as limited edition D34 with a short Lothar Walther barrel of our own design, and a Premium stock.
The internals were then changed to N-Tec as described in the above-mentioned blog entry.
The stem of the N-Tec piston was lubed with Ultimox  PTFE oil and the OEM seal was lubed with powdered MoS2. The central "dead area" of the seal was filled with a UHDPE bumper.
Piston's skirt  was buttoned with UHDPE.
Trigger sears and stem button were coated with dry-lube.
This gun has been tested under fire in a few FT Matches, taking 2nd in the 2016 NY State Championship Open Piston class with a score that would have been middle of the pack with the PCP's:

As you can see, the temperature was -8.9°C (let's call that 264°K or about 16°F)

Freezing, yes, but not as cold as the Minneapolis winters.

Then we shot three shots for warm-up/conditioning that read: 764, 777, and 787 fps

Once we were out of the "cold bore" scenario, we shot a 6 shot string:

As you can see, the average velocity was 788 with a Std. Deviation of 4 fps. Pretty much in line with the humid, hot performance, and 17 fps under the peak performance in optimum conditions (cool, & dry). It may sound high, but in reality it is only a 2% difference.

So, if the Gay-Lussac Law had predicted something like a 13% difference in the gas spring pressure and therefore a similar reduction in the spring force, what happened with the 11% here?

Of course when hunting, or even when shooting FT, you do not rely on taking 3 shots to then take your "for score" shots. Your gun needs to be able to shoot within reasonable limits even if the next bunny or squirrel (whether metal or not) does not present itself in a short time.

So, I left the gun out and waited ½ hour, these are the results:

As you can see, the first shot from "cold" was 781, the next one was again 787 fps.

And not happy with only these results I set the gun outside to wait for the next target a full hour, and this is what the gun gave:

The first shot was 782.

Now, in REAL terms, ¿what can we expect from a change in MV of about 5 to 6 fps (from 788 where we did all our zeroing and trajectory to the first of string "cold" shot of 781-782)? Assuming we are ethical hunters that check their zeroes before actually starting to hunt and possibly, check the trajectory as well.
From actual shooting and using PP-Calc, I know that the H&N FTT pellet out of this rifle gives a BC of about 0.04 (yes its a good one).
And that, using a 37 yard zero with a Kill Zone of 1" (½"up or down from the LOS). gives me a PBR of 43 yards.

Even in the worst of cases, if I used my "peak performance" data, I would still be pretty close:

So close that. in fact the difference in drop at 43 yards is less than 1/30"
I would have to be shooting at 60 yards to have one pellet diameter of difference.

So, why do some gas spring guns live up to expectations and some others don't?

Where is the difference between the 2% MV loss and the 13% loss of pressure?

PROBABLY, and this is only a hypothesis because I can only talk about my gun and I will not generalize one way or another, the difference is in what my UK friend Tony Leach calls "The Lost Volume", that is: that swept volume of air that does "nothing" to propel the pellet because it is produced "in excess" under "normal shooting conditions". In other words, this gun may not be operating at PEAK EFFICIENCY, but it is operating at the PEAK STABILITY.

And THAT, my friends is what matters most in reality.

Over the 18 years that I have been dealing seriously with airguns, and the 6 years that I have been doing this professionally, I have learnt only TWO things:

1.- That pellets do NOT like flying faster than 875 fps
2.- That the devil is in the minutiae.

ALL those little details that people tend to disregard as "unimportant", or as "secondary factors that are material and design dependent" are what makes or breaks the reliable performance of an airgun.

Keep well, keep warm, and shoot straight!

HM