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The Gunsmith's Tune; Part 2/4.- 12 ft-lbs Walther LGV

9/29/2020

0 Comments

 
DISCLAIMER.- The operations performed in this rifle void all warranties. Nor I, nor anybody else, has control over what each individual decides to do, so no warranties are given, or implied. It's up to each tinkerer to be safe in his/her endeavours.
The modifications performed were safe within the objectives and the context of the gun in question.
Which may not be exactly the same as yours.

All machining operations carry some risk, be safe, be careful and always err on the side of caution.
When working with open flames, specially the high temperatures one, extra care needs to be taken with all liquids and gases present in the area. Do NOT risk it.


For those that do not like to devote time to reading long blogposts, let me save you the hardship:

It didn't work.

For those that enjoy the trip more than the destination, welcome aboard and read on!

As any "de-tune", this started by cutting down coils from the Titan #1 spring.
I will assume that readers are conversant with the operations of cutting, sanding/grinding, forging closed and then squaring an airgun spring. So I will skip those details.

Where we left last entry was that the QYS's were coming out of the muzzle at 879 fps ± 3, and BHE's at 876 fps ± 3. With a pre-load of 64 mm's
The goal was to get MV's of 797 fps for the QYS's, so we cut off two coils. Now pre-load was 47 mm's and MV's were for the QYS's: 877fps ± 6 and the BHE's 870 fps ± 4.

So, two coils off and we only lost 2 fps????!!!!!

We took off two coils more, this time pre-load was 29 mm's and MV's were 838 fps ± 3 for the QYS's and 796 fps ± 5 for the BHE's

Since we were still some distance off the goal, I took off one more coil. Preload was now 18 mm's and MV went down to 766 fps ± 3 for the QYS's and 729 fps ± 3 for the BHE's.

To recover some of the MV, I added a 0.081" spacer at the bottom of the spring, and that drove the MV's to 801 fps ± 3 for the QYS's and 757 fps ± 2 for the BHE's

With those uniformities, I had high hopes for the de-tune. so I started shooting test targets. This is where we were in for a disagreeable surprise.

But let's get to the pictures:
Picture
Tested the QYS, JSB 8.44/4.52, and the JSB 8.44/4.52. While short range tests were interesting, at 40 yards the whole thing unraveled.
I thought that indicated that we needed to treat this gun as a different gun, and so we were back to square 1 testing different lubes in the pellets:
Picture
It seemed that the barrel really liked Pledge as a lube, so we tested different pellets:
Picture
But again, at 40 yards the whole thing fell through.
And so I decided to test something else, the harmonics tuner:
Picture
The fact that the HT made little difference told me that there was something wrong.
Completely frustrated, I decided to test myself, and this is the benchmark:
Picture
As you can see, it was not a shooter's problem.
I started thinking that the spring and the guide were simply not in agreement with the rest of the gun.
What followed then was to check the gun with a Walther kit, to see how it behaved.
And so, I installed a Walther 12 ft-lbs kit (piston, spring and guide). MV's were quite satisfactory:
QYS's: 786 ± 5
JSB Xp: 825 ± 3
JSB Xact: 786 ± 2
Testing pellets with the barrel's preferred lube:
Picture
Indicated that at this power level, the light Express pellet was performing better, so I decided to tune the HT to that pellet, with this process:
Picture
From this test, I selected the setting of the HT at -5.14 mm's and proceeded to shoot some medium and long range tests:
Picture
Again, while results for 19 and 39 yards were satisfactory, when taken to 50 yards, the results were poor.

So, clearly, this barrel simply does not want to perform at long range at this power level. Yes, there are barrels like that. I would say that MOST barrels are like that.

CONCLUSIONS: 


While it was somewhat disheartening to see the good behaviour not carried out to the low power level, it did confirm that the ABP, as a technology, is more reliable at these power levels that a large pre-load.

I have reverted the gun to its higher performance and, MAYBE in the future, I will shoot a "Hunter" course with it, as the performance of the slightly heavier pellet at the limit of stability is indeed interesting.

And, so we learn more from our "failures" than from our successes. Yes that is science, that is life.

Next will be the application of these findings to the 430L.

Keep well and shoot straight!





HM
0 Comments

Mandarins to Oranges

5/26/2020

4 Comments

 
INTRODUCTION

Most of you will know me as a "Science guy" and, yes, I guess I am more than a common NERD.

But life and experience have taught me that there is a lot of worthwhile knowledge to be gained from just listening to the users. Especially if the users are experienced and UNCOMMON
 persons, in the sense of having been endowed with more than a passing grade of "COMMON SENSE".

When I was much younger, my GrandMa used to tell me that the least common of senses was the common sense. After almost 64 years I have come to agree wholeheartedly with that.

Bill and I met by "accident" in one of the fora, we both love airguns, and German Airguns more precisely; and I cannot but see a future me (result of a strongly driven and purposeful youth with lots of physicality to it) in him.
One day my body will present the "bills" for all those strenuous activities. 
And, while growing old is mandatory, it's growing up what I plan on keeping "optional"  ;-)
​
To keep a capacity of wonderment, and the love of life, is what will make the next decade (or two), what it is supposed to be.

And so, in that spirit, I present you with a notable person, in the sense that he makes a lot of sense.

Oh!, and what does the title mean? Well it's sort of a private joke because while discussing the idea of this Blog entry, Bill asked me (and rightfully so), "Won't we be comparing apples to oranges here?"
My response was that there were sufficient characteristics shared by BOTH guns (HW30 and AM03)  to think more about a comparison between Mandarins and Oranges: about the same, just slightly different size, zest and flavour.

¿Isn't that what life is all about?
​
;-)

I yield the floor to Bill:

Guest Blog by Bill Rickvalsky

Picture
Bill with the two guns he was charged of comparing: in his left hand, an HW30, in his right a modified DIANA Mauser AM03
Let me begin with a little background information. A few weeks ago I was involved in a discussion on a web forum about the possible acquisition of another air rifle. I had not too long ago acquired a Weihrauch HW30S as an addition to my Diana Model 34. The reason for that purchase was because the cocking effort of the Diana 34 had become rather fatiguing. The HW30S was a considerable relief in that regard. But then I began investigating the purchase of another rifle that might provide power similar to the Diana 34 but not be as difficult for me to cock.

The reason the cocking effort is an issue for me is that I am in my 70's and have a chronic health condition that occasionally affects my muscle strength. But I thoroughly enjoy my shooting and regularly have somewhat lengthy shooting sessions. The HW30S allowed me to do this without wearing myself out.

As a result of that forum discussion I was offered an opportunity by Hector to compare my HW30S to a Diana AM03 Mauser that had been modified with people in just my situation in mind, older folks with health issues. The AM03 started life as an NTec gas piston rifle. It now has a steel spring operating an anti bounce piston (ABP). The rifle is putting out 13 fpe and has a cocking force of 23 pounds. My objective was to report on the perceived cocking force and the shooting characteristics of this rifle and the HW30S.
Picture
From top to bottom: DIANA Mauser AM03; DIANA 34; HW30S
​After receiving the AM03 and getting it set up to shoot everything went very smoothly and the rifle fit me well just as received. My quick impressions from the first shooting sessions were very favorable. The AM03 is heavy. The all up weight is 9 lbs. 11 oz. which is heavier than my Diana 34 at 9 lbs. exactly. My HW30S weighs in at 6 lbs. 12 oz. Both rifles are scoped. The cocking effort of the AM03 was perceptibly heavier than the HW30S but not by a significant amount. The difference between the two would not make me choose one over the other just based upon the work involved in cocking. My Diana 34 is significantly more work. The trigger on the AM03, which I understand is an Ntec T06, is very light and has a clean, crisp break. A very nice trigger so I can't blame my sometimes poor shooting on the trigger.
Picture
Do any of you think this is poor shooting? Heck, No! It's good shooting in anybody's books.
As I was able to get in more shooting sessions I was paying particular attention to the shot cycle characteristics. The AM03 seems to shoot at an equivalent power level to my Diana 34 although my chronograph is not operational I had previously determined my Diana 34 put out about 13 fpe.  But the shot cycle characteristics were very different. The AM03 has a sharper, crisper shot cycle than either the HW30S or my Diana 34.  By that I do not mean the shot cycle is harsher. It just seems quicker and more stable. While the HW30S has a softer shot cycle it is only about a 6.5 fpe rifle. My impression after several shooting sessions was that the AM03 is less hold sensitive than my Diana 34 and is almost on the same level as the HW30S in that regard.

A couple of the shooting sessions I had were fairly lengthy with over 200 pellets down range. On those occasions the cocking effort of the AM03 and HW30S became an obvious advantage for me. I believe I could shoot either of those rifles all day long. I eventually would lay the Diana 34 aside while shooting the other two. I know there are people who do not find the Diana 34 difficult to cock. But it apparently crosses a threshold of work for me. I like the rifle and can shoot it for a while but there are limits. 

One side comment I would like to make here is about the length of the cocking arm (barrel) and how it affects this. While many people say the longer barrel provides more leverage it also requires a longer reach, particularly when sitting. When reaching up to the end of the barrel my arm is fully extended and then has to swing out and down while still fully extended until more than half way through the cocking  cycle. This actually is as much of a disadvantage as it is an advantage. I find it easier to not reach all the way to the end of the barrel.

Someone else's technique may give different results in this regard.

Picture
The AM03 seems a little louder from behind the gun than either of the other two rifles. It is not very much at all and may be related to the crisper shot cycle. But I am fortunate in being able to shoot without any concern for the noise levels of any of these rifles as none of them is really offensive in my rural neighborhood. And just as a check I asked my son to listen to them from about 20 yards away to the side. He felt that the Diana 34 and the AM03 were about the same. The HW30S as expected is quieter.

I would love to have a hybrid of the AM03 and the HW30S. I like the extra reach of the AM03 without paying a significant price in cocking effort. The AM03 that I am shooting is heavy, especially for occasional offhand shooting. But there are times I wish the HW30S had just a little more weight for offhand shooting. This light, short rifle sometimes seems a little twitchy without a rest of some sort. It would also be nice to have the barrel on the AM03 be two or three inches shorter. For me anyway the shorter overall length would balance better.

Picture
I would like to thank Hector for this opportunity to participate in this comparison and to possibly contribute slightly to upcoming design decisions. And I told him several times how much I love the set up on the trigger in this AM03. It is an absolute pleasure to shoot. 

I hope everyone learns a little something from this old guy's comments. I know there are others like me out there who may have the same concerns. 

Bill Rickvalsky

​

N.E. I would like to finish this entry by thanking Bill for his time and effort.

And yes,I learned things that we expect to put in place with the new EMS line at DIANA.

The 34 EMS will allow users to "tailor" the gun in such a way as to suit THEM.

Particularly in Bill's case, I am already envisioning a 34 EMS with the NTec trigger, a lightweight ABP unit inside the OEM piston, a shorter barrel, and a Carbon Fiber moderator/Harmonics Tuner in place. The short barrel will save 1 full pound of weight, the Carbon Fiber mod/HT will save another ¼ lb, and a beech stock will also save another ¼ lb, so, all in all, with a Traditions lightweight scope in small ZR Mounts, we could be looking at a 7 to 7¼ lbs all up rifle still capable of delivering 12 ft-lbs at the muzzle with a bit over 25# peak cocking force.

Now, THAT would be an interesting little gun, LOL!


Keep well and shoot straight!





​HM
4 Comments

New "Super Custom" trigger for the Walther LGU/LGV

4/29/2020

4 Comments

 
BEFORE ANYTHING ELSE, I am required to post this, the legal disclaimers:

1.- Swapping the trigger blades WILL invalidate the warranty of your rifle.
2.- ANY user intervention in the triggers 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 MY gun. I cannot guarantee that it will be the same in YOURS.


Back in May 2018, I wrote a note about the then available "Super Custom" Triggers for the LGU/LGV rifles.
In the original post we discussed European versions, but on this one we will discuss an American design.

For those that have not followed my interest in these fine guns, I would suggest you take the time to read these entries:

https://www.ctcustomairguns.com/hectors-airgun-blog/the-walther-sport-family 
https://www.ctcustomairguns.com/hectors-airgun-blog/swapping-the-walther-lgus-trigger 
https://www.ctcustomairguns.com/hectors-airgun-blog/a-yankee-tune-for-the-walther-lguhttps://www.ctcustomairguns.com/hectors-airgun-blog/a-yankee-tune-for-the-walther-lgu-second-version 
https://www.ctcustomairguns.com/hectors-airgun-blog/the-walther-lgv-a-second-look 
https://www.ctcustomairguns.com/hectors-airgun-blog/the-walther-lgv-pushing-the-power-limits 
https://www.ctcustomairguns.com/hectors-airgun-blog/the-supercustom-triggers-for-the-walther-lgu-and-lgv

As you can see, I am a great fan of the LGV, considering it the best breakbarrel rifle in recent production. We would have to go a few decades into the past to get something better.
These models had been in production for less than 6 years, and in those 6 years, not less than 4 trigger blades came into the market, WHY?
Savvy airgunners have been
 puzzled about how could Walther put such a bad trigger on such a good gun.

And here is where I sometimes ask myself questions that I know would be very "uncomfortable" for a manufacturer to answer, but that definitely point to a marketing strategy that fails to take into account the simple truth that "There are no second 'First Impressions' "

If we analyze the cold facts, they are:
- Rifles are very good rifles, among the breakbarrels, the LGV has no peer. The LGU faces stiff competition from other fixed barrel rifles that are just as good, if not a bit better, depending on the criteria used for judging.
- Price, when they hit the market was high. Granted, ALL airgun prices were high back then; in general, prices have come down as demand has grown, production volumes have gone up, and more brands/models are available.
- Simultaneous to the launch of the rifle itself, Walther launched a "Match Abzug" (MA) that promised a better release but, again, price was high.
- In at least one market, the rifles were ONLY available WITH the MA, at considerably higher price still.
- At some point, up to 6 different "variants" were offered of the LGV. From "De Luxe" models to "Workhorse" models.

To be honest, as a marketing strategy, this is a recipe for trouble.
Those that could ONLY buy the expensive versions thought about it and probably didn't, or if they did would always question their decision.
Those that bought the "economy" versions would not buy the accessory trigger.

Everyone agreed that the guns were between good and great, but still the market response did not justify the costs of production, one by one, the different variants of the LGV were dropped. Unconfirmed information says that Walther has decided to discontinue ALL breakbarrel rifles. Even when the attempt was never made to market the "Century" (a sort of economy LGV with all the good characteristics, but none of the fineries) in the USA
Which is a pity.

And it is what brings us to this entry.


As with many things in this "CoVid-19" world of "stay at home and do something", some people with the skills and the machines in their workshop now have the time to actually do some serious stuff.
In my cybertravels through the airgunning community, I came across an interesting post about "yet another offering for triggers" for the LGU/LGV, and it piqued my curiosity.

And this is how I met Eric. Eric lives in Texas, and he is a great guy. Modest and unassuming, it's a pleasure to deal with him. He is also talented. At first he said he had developed another trigger for the LGV/LGU rifles but that he needed to polish some aspects, a few months later, he comes up with fully finished prototypes. So many corporations would LOVE to have that time of "Start to Finish R&D", LOL!
SOooooo...
Let's get to the trigger:
Picture
As you can see, it uses a quite novel way of making it adjustable without making it expensive. At $80 retail, it is in line with what European triggers cost, and it does provide some advantages.

Among the advantages: there are two possible positions for a second stage, one that provides for a light pull, and another one that provides for an even lighter pull, at the expense of a little "crispness".
In a way this is similar to the Rowan Engineering version, but if we compare them side by side they are not quite the same:
Picture
From left to right: Walther's MA, Eric's trigger, and Rowan Engineering (RE) Trigger.
While the RE trigger allows the user to move the whole trigger blade back, it also ends up needing a "shoe" that is far too wide to operate/work on the trigger. If you want to remove the stock, or adjust the second stage (in the "heavy" position), you need to remove the blade and the holding post.
Eric's trigger does away with that.
Eric's blade is further back, and one of the common complaints about the LGU/LGV stock is that the pistol grip is really big and seems to be made for giant's hands.
Some shooters (even one previous World Champion) hold that huge pistol grips prevent the shooter from inadvertently twisting the gun when releasing the shot, and that is very true, but it is also true that techniques exist to teach ourselves to apply a slowly increasing force that does NOT twist the gun and therefore does not affect the shot. IN any case, the most common versions of the LGU that you see in the competition circuit have ALL had their stocks replaced.
As far as adjusting the distance between pistol grip and trigger blade, Eric's trigger uses a novel approach, and that is a pressure plate that can be moved in/out meaning that it shortens or lengthens that distance.
Eric's trigger is also a bit more swept back, and so the pressure plate could be used as a "Register Mark", ensuring uniform trigger finger placement.
Picture
When comparing the positions of the three screws we see that RE's trigger uses a fairly uniform spacing between screws, whereas Eric's trigger uses a skewed distribution that, while providing for an even "lighter"  trigger pull, will definitely loose some "crispness" to the release.
We also note that RE's trigger has rounded screw faces, while Eric's trigger has pointed faces. This is a result of the market they are oriented at; RE's trigger is sold mostly to fairly amateur airgunners, as a "drop-in", while Eric's trigger assumes that users have ALREADY taken the time to stone and polish all interacting surfaces.

Yes, if you are looking for the LIGHTEST possible trigger pull in an "untreated" trigger block, then RE's trigger will give you that, BUT, if you are looking for a compromise between extreme lightness and total crispness and you are willing to stone and polish your trigger parts, or send them out to a Pro, then Eric's trigger can more easily accomplish this, and with less fuss because you can adjust all aspects of the trigger pull with the trigger blade in the gun, without the trigger guard (more on that later).

To install Eric's trigger is simple; you take apart the gun and when you have the trigger block out and the clamshell disassembled, you take out the old trigger (on the left is the OEM "economy" trigger with the lengthened screw of the "Yankee tune", on the right is Eric's trigger):
Picture
And put in the new one:
Picture
Eric recommends cutting one coil of the extension spring that is the return/no slack spring, but I did not find it necessary.
You will need a crochet hook or some other hook to get that spring out and then in again, so DO REFER the blog entry about "Swapping triggers" above mentioned.

Once you have swapped the triggers, you will need to adjust the screws.

Eric sends a very interesting manual that details STARTING points for the protrusion of those screws and I found the manual absolutely right. SO, DO READ IT!

Once that is done, you can close the gun and start the actual fine tuning.
Picture
It's important to note that once assembled, the gun should be checked that everything is in its place and the clamshell is properly closed and aligned.

Upon some extensive testing, I found that FOR ME, the flat pressure plate gave a "strange" feel, to the point of being distracting, because the pressure plate always keeps the same orientation, when lowered to the last hole, the feeling was that I was pulling in a "crooked" way.
Picture
While this would be ideal for shooters with custom stocks that almost always have a "vertical" pistol grip, it was somewhat off-putting to use with the sporter stock.

So, Eric agreed to make two versions: one with a curved blade, and another with the "flatish" trigger blade

I found also another solution that is truly viable only at very low trigger pulls, and that is replacing the screw with a button headed allen screw that presents a hemispherical shape to the touch of the hand:
Picture
The other thing I like is that I can use a locknut at the rear, to ensure that the setting does not get "out of place".
At trigger pulls above 1# this is somewhat tiring in the long run, but below that it is an eminently usable solution.

If you note, here I have a fully assembled and functional gun without the trigger guard, how is this possible?
Well, Eric designed and will include as part of the kit two plastic "D"s that allow you to get the gun back together to the point where you can actually shoot it, and still have completely open access to the screws for adjustment.
You can see one of the "D"s in the picture above.
​
I tested the trigger in an "untreated" LGU trigger block (my LGV being "on loan" for a lengthy and really serious experiment), mainly to see what difference the 40-60 minutes of stoning and polishing parts would gain a shooter, but also to get a feeling of how narrow the market would be for Eric (difference would be between a few hundred to a few thousand).
And I found out that the lightest trigger pull I could get was an extremely rewarding 1# 2 oz. with great consistency.
Almost anyone should be able to live with that.

In a stoned and polished trigger block, pulls can be lowered to levels that I would not consider safe for 90% of the shooters (just watch Eric's video referenced below), but in the end it is each and every one of us who are responsible for our actions.

Eric has also agreed to send, to those that request it, a "ball end" for the pressure plate, something like this:
Picture
Have not tried it, but it makes a lot of sense.

I was very happy to work with Eric on this project, and since he is still in the pre-production phase, there are some changes that will be inevitable.

BTW, you can see Eric's video here: 
https://www.youtube.com/watch?v=jvndvLfzug0&feature=youtu.be

If you are interested in finding out more about this trigger, or if you want to buy one, drop Eric a line at:
epianori@gmail.com

Let him know you saw this, please.

;-)

Keep well and shoot straight!




​HM
4 Comments

The "HPM" or DIANA's High Performance Muzzleweight

4/25/2020

13 Comments

 
I have received some questions about this system (yes it is a SYSTEM), as well as a specific request from one of my favourite persons in the airguns' cyberworld, and the questions tell me that without the IWA 2020 happening, a LOT of what WE (DIANA) had hoped to relay to the users and accomplish on the shooter's information side simply DIDN'T  happen.

Questions also tell me that people are not really up to date about where the research and development of spring guns is going. In a way, that is understandable, manufacturers are not doing the best of jobs in telling people how more advanced today's spring guns can be in relation to those airguns that the Cardews' analyzed in their legendary works.

So, let's look at a little bit of history and how it percolated into the production line of one of the foremost examples of applied technology in the spring-piston airgun world, then we'll look into more recent experiments, and how, finally, the product became a system to be included into the new edition of the Air King (the AirKing Pro). Along the way, we'll discuss how sometimes even manufacturers fail to recognize the DIFFERENCES between an airgun and a firearm.

So, let's get started:

A bit of history

Ever since my powder burning days (1966 to 2000), I have been a firm believer in tuning the gun to the projectile, and choosing the best projectile to the task at hand. If you are familiar with the "Accuracy Node" concept, you know that all rifles have a MV where the bullet exists at the point where the barrel's muzzle's excursion is at its extreme. Meaning that it is going in one direction, stops, and then starts moving back. Like a pendulum, but in a much more violent manner. So, following that methodology, the MV of airguns can be changed in small increments through the use of spacers in the spring, so that the pellet's exit coincides with the end of the oscillation where the transversal velocity of the muzzle is as low as possible because it's either stopping, at rest, or just starting to accelerate back.

Therefore, when I came across a commercial unit that offered to do that for the DIANA's  I jumped into it. Over time, I found the unit somewhat fragile and capricious (getting out of adjustment at the worst possible time), till at some point, I had it glued (this commercial Harmonics Tuning product was discontinued about 15 years ago), then in 2015, as a result of its dismal failure in a WFTC Match, I decided to design something that would work in my favourite platform, the DIANA 54 AirKing.

Some time passed and I then came onto the realization of a basic characteristic of the DIANA 48->56 family: The barrel is in reality a 15.2 mm's barrel that has been encased in a shim and then that shim goes INTO an 18 mm's  sleeve, that is what we see. That is the nicely blued part that we take for a barrel, but it is not.

In the past, SOME shooters used to fill the cavity between the shim, sleeve and barrel with resin, or other compound, and claimed to have improved the accuracy, but my problem with that approach was that it was a FIXED solution. "Tuning" of your system would STILL need to play with the MV and finding the "right" pellet.

I wanted a simpler device, something that would allow you to re-tune the gun should you change pellet batches, or wanted to change brand, power level, or any other thing. Something that would allow you to set a velocity (according to some rules, or other criterion set by YOU), and then tune the gun to THAT. In other words, command the gun and not be commanded by it.

I looked at all the existing Harmonic tuning systems (firearms, archery, and airguns) and all but one depended on a weight that was knurled and screwed or unscrewed along some position in the barrel, or a rod. The one that didn't, depended on moving the support position of the barrel in the stock (forend pressure point bedding) therefore lengthening or shortening the free-floated length of the barrel, problem was that most spring-piston airgun barrels are free-floated by design.

So, I decided to combine both concepts and came up with a system that is comprised of a specifically dimensioned weight that can move back and forth along its position on the barrel with set spacers.
I worked through a few prototypes and when I had settled on something I published my results here in this blog entry.
Now, do note that this happened in 2016, that's 4 years ago!

Since then, most of CCA builds have benefited from this "gadget", and/or from the knowledge and techniques that this research brought. Further research has been done and now we know not only how to control, but how to REDUCE the harmonics at barrels' muzzles (though that is another story ;-) )

Almost three years ago, I started working closely with DIANA, and since there were talks to bring this technology (and others) to the public/shooters of DIANA airguns, I did not pursue further the commercialization of the product.

So, when the time came to write the spec for a "new" 54, it was normal for me to include this device into the spec. In complete agreement with DIANA, we decided to name it the HPM (for High Performance Muzzleweight).

The first appearance of the device to the public under the DIANA brand was at 2020 SHOT Show, there is a whole thread about it here where you will find links to videos, reviews and other comments; as well as a lot of questions and answers.

And that brings us up to the present

First proposal and a "failure"

It was towards the end of 2019 that I was told that about 300 "54 barreled actions" were available and that we could use those to launch a re-vamped 54.
The problem was that there was NO BUDGET available for improvements. Meaning that whatever we wanted to put in, had to come from reductions and savings in the SAME model, that is a tough value-engineering problem: Improve a product AND make it cost the same or less. Not easy without a technology leap. Still the challenge was taken up by the team and we discussed a number of things that could be improved. Sadly, ALMOST ALL implied some cost increase. The exception was the Harmonics Tuner. A muzzle piece needs to be there, and the plastic one in current production, though not expensive, is not cheap either. It's a complicated mould. Also, the change COULD imply that the "Pro" model would be a scope-only rifle, so the sights could also be eliminated. Lastly, there was an extra operation on the barrel to create the "key" where the front fight ramp/muzzle piece needs to index to always keep the front sight straight up. Between all these "savings" the Harmonics  Tuner seemed to be a good candidate.
It also promised to be the most value for money that would still be useful to ALL shooters (and here I want to remind you that DIANA operates in more than 90 countries with 7 different power levels and some caliber/rifling/OAL legal complications).

And, finally, adapting it to the EMS system would be a breeze, so, after much thought, the concept of the Harmonics Tuner came to the forefront. The part is simple to make and easy to use, it does NOT come out of adjustment, and use tends to affix it more and more firmly into its place.

Simultaneous to that I had started some serious work with a friend with a scientific penchant that tested the usefulness of the Harmonics Tuner in two completely different power plants: A short stroked D56 and the "skinny piston" (22 mm's compression chamber bore) version of the same gun. As different as apples and oranges.
You can read the results of those experiments here:

https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th 
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th4603110 
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th8042880 
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th2541108 

As you can see from the whole SAGA, the Harmonics Tuner proved its usefulness in two completely dissimilar engines. It would be like testing a turbo-charger in a Mack Diesel Tractor Trailer and a Subaru BRZ and still finding improvements in both results.
And the HT was deemed an "easy to use" device, needing the release of the screws, the addition or subtraction of an ORing and the reassembly of the gun, an operation that took less then 3 minutes per test.

So, it was DOUBLY annoying when DIANA's head gunsmith told me that they had not found any change in group size when tested in the factory, regardless of the number of spacers added.  WHAT?
Luckily, the Technical CEO told me that they would still go ahead and planned the use of the device, but that I had to come up with a new design, test and a procedure to demonstrate the usefulness.

After taking a day (or two) to calm down and analyze the whole thing, I decided to question the test procedure followed by the factory. It was then that I was told that the gun had been put on a vise that held the sled system fixed, but at an angle, that changes had been made from the original spec (aluminum instead of steel), and that only two screws, instead of the 6 that were originally specced had been used, granted that perhaps my drawing had not been completely clear, but still the device built by the "Construction" section of the company was not what I was talking about, these substantial changes warranted a re-design and re-test, under conditions that would be found in real life shooting.

And here is where there is a lesson: If you need to test something that is going to be used under field conditions, then test it under the same field conditions.

A new material was sourced as Aluminum DOM bar, and new prototypes were made, but this time complying with the needed weight (one of the most lengthy sets of experiments I ever conducted way back in 2015).
I then prepared a completely new test using one of the guns that were on the pipeline, and these were the results:
Picture
As you can see, adding or deleting ORings yielded observable and measureable results. Dispersions went from horizontal to vertical and then back, and too many ORings (same as too large a weight) produced horrible results.

With these results in hand, I went back (electronically) to DIANA, and it was agreed that the AirKing Pro would come equipped with the device.

The device itself is VERY simple and easy to make. From the outside it looks just like an average Muzzle Weight, but the trick is on the inside, where ORings can be added or removed to determine the position of the weight along the muzzle. In the same way that using a longer or shorter bar changes the "tone" of a grandfather clock carrillon, the harmonics (vibrations) at the muzzle also change and this is what determines the POSITION of the muzzle and WHERE IT IS AIMING AT, when the pellet exits the muzzle.
Picture
Picture
As ORings are added, the muzzle that was flush with the end of the HPM, becomes more and more "recessed" into the cavity.
Using one of Steve's excellent pictures, although that is a steel version of the HPM for the model 56, not the 54, you can see the make up of the whole system
Picture
The other difference you will find is that while 3 screws are enough for 12 ft-lbs, for 24 ft-lbs you need 6.
But the principle is the same: You add or delete ORings to bring down the group size with the pellet you want to use (within reason).
As it was demonstrated and re-tested, in a normal 54, the results were verifiable and repeatable:
Picture

The Future

Picture
Between 4 and 6 months after "re-start" of the world's economy once CV-19 has been overcome, we should be able to see this in retailers and internet sellers.
There will be other options in stock colors and, of course, a beech version.
The process to "tune" the rifle's harmonics will be the same: 
1.-Start from 0 ORings
2.-Shoot three shots into a "waste" bullseye
3.-Shoot a 5 shot group at least 15 meters away (19 is preferrable).
4.- Add one ORing
5.- Repeat from 2
6.- Repeat from 4
When you reach 10 ORings, STOP, you should see a "periodicity" each 4->6 Orings (depending on power level), settle on the two settings that are most promising and re-test till you are happy that you are at the best possible point.

I would advise to "Run in" the rifle BEFORE the tuning (if in doubt about what is the BEST way to do this, read this), as the wearing in of the parts amongst themselves is an essential part of what airguns need to be able to deliver top accuracy, but if you want to "train" yourself in the procedure by all means do it several times. Just understand that, in the end, you cannot put the carriage before the horses.

Hope this answers as many questions as is normal before seeing/handling the actual thing.

Always open to questions or comments.

Keep well  and shoot straight!





​HM
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The SAGA of a 56 T/H

1/23/2020

0 Comments

 

Part 4.- Epilogue

DISCLAIMER;

First of all, an apology. Steve and I started exchanging more and more information and I got carried away on a tangent. He was kind enough to "call me back on track". Perhaps I am too much of a scientist and love bare truth too much. So, I need to rely on good friends to make me see the forest, as I am too entangled in the trees; the delay is mine and mine alone.

What follows are my own personal observations, conclusions, and hopes of further work.
I take full responsibility for what I say or write. If someone demonstrates me that I am wrong, as I have done in the past, I will stand corrected.
Nobody's "Purfect".

Let's re-cap: the FOCUS of this series of articles was the Harmonics Tuner (HT); a relatively simple device that allows the shooter to tune a gun to the best possible performance of a given pellet in the gun, WITHOUT altering the MV.
​
The idea was to compare the performance of the HT under two completely different powerplants to see if there was ANY measureable improvement from both, as different as they are.
As you can see from the results, there is. Smaller or larger, but there is a measureable improvement.
This is what I feel is most original.
Typical airgun tuning is done through cutting coils, change of springs/guides, change of pellets, and adding or removing washers that go from full sized spacers to paper thin power adjusters. BUT that means altering the trajectory (because MV changes) so that accuracy can be obtained.
The HT, in a way and within reasonable limits, allows us to "have our cake and eat it too"; because we can select an MV (obviously within the stability range of the pellet we want to use, and assuming that the barrel does not deeply dislike the pellet), and THEN tune to optimal accuracy and precision (depending on what we want to do with the airgun) to the best possible results within that system.

I have also received "questions" about the validity of using 5 shot groups as "data points" being that sometimes variations between groups are as large without any change, as they are when performing small changes. As limited as our tests were, we are confident that the results are reproducible in any individual's airgun, as long as the proper procedures are followed. 
​The RESULTS for individual guns may be different (as is normal with most aspects in airgunning), but everyone can find an "optimum spot" for harmonics tuning.
​That is part of the essence of the beast.

So, having clarified all that, let's get going
Balance

I have found that in life, BALANCE is a useful concept. You need a Work/Life Balance. You need to keep a proper Financial BALANCE. You shoot better when you exercise your BALANCE. You can see the dynamics of phenomena more clearly when you look at the BALANCE of Energy and Matter.

As a person, Engineer and Scientist then, BALANCE became my "standard" way of analyzing things, evaluating things, and making decisions. From daily spending to complex physical phenomena, everything gets analyzed as a BALANCE relationship.

I like to look in detail at what I put into an airgun, and what I get back. In this sense, the HT demonstrates that for relatively little effort (as Steve has shown), substantial changes can be obtained AT THE TARGET. No need to disassemble the gun and play with the MV.

As per Steve's data, the biggest difference between the largest and the smallest group with the different powerplants was of 2 pellet diameters in one case and 3 pellet diameters in another case (at 32 meters).
¿For an hour of shooting and testing different "degrees of separation"?, I would say it is time well spent.
​
Sure, as airgunners we might even finish the lot of pellets we are using in testing and re-testing and we'll need to go get another lot . . . just to start again, LOL! But the facility this device gives is an interesting addition to the "airsenal" of tools that airgunners have.
Commercial Availability
As of this year, the HT will be offered by DIANA in the "New Version" of the DIANA 54 as was launched at SHOT Show 2020
It will be a model designed for the 54, as opposed to the 56 that Steve tested so, much shorter and made of aluminum.
We'll probably call it the "HPM" for High Performance Muzzleweight  ;-)
Picture
We might make some tweaks still, as this is a pre-production model.
​We are working on making the HPM available as an after market part for ALL 54's (as usual, in good DIANA tradition, it will be fully compatible with all previous editions of the 54, though the T01's may need a little gunsmithing).
I am told that the stock will be available in several colors and that also more traditional Beech (and perhaps some Walnut) stocks will be made available. It all depends on the wholesalers, so if you are interested, write to your favourite wholesaler to request some attention to the point of your interest.
Steve and I have been exchanging a lot of interesting information, and I have also been receiving results from the Harmonics Expert, such as this:
Picture
Accelerometer Plot of g's vs. time for an ASP20
So, I will be writing another entry, this one dedicated to a more detailed and better analysis of what TRULY happens with the spring-piston shot cycle, what determines the efficiency, what are common misconceptions about it, and analyzing more in depth the "phases" of the shot cycle.

Just to give you an advance taste:
The curve above belongs to an ASP 20
You can clearly see that the first acceleration spike (red oval) is where the piston reaches the end of the air compression run, and that a few msecs later (green oval) there is an even greater "slam" BUT, the human senses cannot detect it.
You can also see the 70 g's force vibrations developing during the time of the pellet in the barrel (-20 to +50 g's for 7 msecs, though the dwell time of the pellet in the barrel is shorter).

It takes relatively sophisticated instruments to detect and measure them, not only in magnitude, but also in time. The chart also shows a good, long decaying vibration pattern (blue square).
And all this from a gas spring gun that has been reported as a "smooth shooter" and excellent at bench rest.
¡Surprise!

Anyway, it will be fun to actually make the real behaviour of the shot cycle evident for different airguns. And to see what works and what does not work, independent of what shooters "feel".

Conclusions:

The HT is a device that has been tested and proven in different power plant designs and has proven its value.

​DIANA will include it in the next " edition" of D54 rifles.

There are still other technologies that await research; as long as there are people that are fascinated by the spring-piston airgun, whether it is a steel spring, or a gas ram, there will be things to discover and improve.
And THAT is also part of the magic of airgunning.

Again, I need to thank Steve for his excellent participation and impeccable work. It has been a great pleasure working with him on this.
And also thanks to our readers because without dedicated airgunners willing to read a LONG, FOUR part, entry our words would be like the sound of a tree that falls in the middle of an empty forest . . .

Keep well and shoot straight!






​HM
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    Hector Medina

    2012 US National WFTF Spring Piston Champion
    2012 WFTF Spring Piston Grand Prix Winner
    2013 World's WFTF Spring Piston 7th place
    2014 Texas State WFTF Piston Champion
    2014 World's WFTF Spring Piston 5th place.
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    2015 New York State Champion WFTF Piston
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    2018 WFTC's Member of Team USA Champion Springers
    2018 WFTC's 4th place Veteran Springer
    2020 Puerto Rico GP Piston First Place
    2020 NC State Championships 1st Place Piston

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