Hector's Airgun Blog

The Chronology of Chronos

3/30/2025

Disclaimer:
1.- The items analyzed here have NOT been sponsored in any way form or fashion.
They have been acquired over commercial channels under CCA's own resources.
No comment is made with the intention to endorse or deprecate a product.
These are our factual findings.
YMMV
2.- This note is written from the POV of a gunsmith that needs solid information in the process of the development of a project.
An old FT competitor once said: "He who lives by the Chrono, will die by the Chrono" and that is true once you get out in the field and do actual shooting.
As important as chronos are to me when used as tools, they do NOT guide the philosophy of a tune, or the settings for a gun.
Always remember that the chrono is a tool, YOU are the one that needs to take the decisions for what to do with a specific rifle based upon the task at hand and the capabilities of said rifle.

A bit of history

I've been interested in ballistics for as long as I can remember, made my first "catapult" at around age 3, and had my first toy mortar for my 4th Xmas.
From there to the "Atomic Cannon", bow and arrows, BB gun, first Crosman Pellet gun, then onto RF, CF, and all the way to whatever you can think that can be shot from the shoulder.

And I have always been of a very "curious" nature. Dad used to call me the "Boy of the Why's"
(Now I am paying for all I did back then, but that is another story, ROFL!).

So, when an elder cousin that was already in Engineering school told me that ballistics was all about the projectiles' speed, I started looking for ways to measure it.
.
.
.
Without success.
Truth is that measuring fast phenomena is hard.

By the time I was in Engineering school, and my shooting interests had gone all the way into reloading and bullet making (both, by casting and by swaging), I needed something that gave me some reasonable idea of where we we were at.

Looking around for ideas, I came across a note by some European ballistician that talked about "tape breaking" chronographs. Some research through the University Library, and some actual letters sent over "the Pond" through postal services, returned an exorbitant offer for a device that would measure the speed of a bullet by setting two "gates" (really just pieces of tape that were metal zig-zag strips sandwiched between cellophane tape) at a known distance apart and using an electronic chronometer to measure the time it took the projectile to travel between the two "gates".
Back then (1974-1975), the best electronic "stop watches" we could get were in the MHz region (about 1 million cycles per second), and those were expensive.
BUT, the oscilloscope of the lab was capable of much faster readings. Problem was that it needed a 120V outlet.
And, so, after making an experiment at the lab (with my old Crosman) and ascertaining that it was useful, I splurged the equivalent of US$125 in a battery driven Chrono that would have a frequency of ¼ mHz (that is 250 kHz).
Spacing the "gates" by 4 feet, I could measure pretty good velocities., though the precision was not extremely good.
Let's assume I was checking on a Standard NATO cartridge, that has MV's of around 2,800 fps, that would mean that in 4 feet, the chrono would count 357 cycles.
BUT, for each "partial cycle" that got counted or not, the difference to the true MV would be of about 17 fps.

Good enough for developmental work, but far from ideal.

The MAIN issue however, was that each shot fired, required a walk in front of the firing line, which meant a cold line, and 3 minutes to reset the tapes.

So, to chrono just a string of 20 shots, took an hour.

I was happy to do it, believe me. I could talk about real numbers, with known errors, and that put me on equal footing with many writers and some technicians working in the official and commercial fields of ammo making.

Of course I dreamt about purchasing an Oehler 33, and then a 35, but life got in the way, and I would dedicate less time to developmental work and more to actual shooting till I graduated and came back from England.
By then, I had a solid job and could easily spend the nearly US$400 required, Competition Electronics was already a well established company and the compact "light screen" chronos were a reality.
It took the world 14 years to actually get to the point where the "average Joe" could measure the velocity of his projectiles, and by 1988, I had ordered one that I received courtesy of a friend that had a friend with an address in NY.

I used it extensively and cherished every moment.

I still have it, and it still works!

It's two feet long, weighs two pounds and the screens are minute (about 2"X 4").
Talk about the "pucker factor" of shooting through such a small window.
AND you had to keep at least 10 feet between the muzzle and the Chrono!

Get all the white lines aligned and make double sure that you are using the right LOS height.
;-)

I went through several of the black cardboard "markers", and the top difusers were easy to make from plastic paper used in pro drafting.

It served me well until 2010, when in a trip to the US I was able to get the "current generation", which boasted IR detection (a problem for spring-piston airgunners, as we will discuss later), and could use powered light screens, no more waiting for daylight to do the measurements, no more hoping for a day that was overcast "just right":

This one, of course, was used and abused for the following 13 years.
Problem is: that one stopped working!
Competition Electronics offered no viable solution, perhaps based on the fact that it was well over a decade old, they suggested getting another one.
:-|
Well, that does not fly with me too well, so I cast a research net and came across what was supposed to be the most accurate of the "amateur" models, and I got it:

Over the last two years it has proven reliable and useful. A peculiarity is that, when using the wires to feed the IR screens, the screens come closer to each other, and so a "spacer" was added to maintain the correct 12" of distance between the two screens in order to get accurate results.

For a while, all was well in the World, but then, the connection between the Chrono and the computer/phone stopped working. Tried a BUNCH of solutions. Different phones, tablets, reloading the app, etc. But to no avail.
After calling the Caldwell people and laying down the problem, they said "Yes, we know about it, but we don't have a way to update the app, Android has changed and we cannot do anything about it".
Supposedly, they were going to call when some remedy was available, but so far . . . . crickets.
The MAIN issue here is that this model was designed around the app. AND, without the app, there is no local memory, nor computational capabilities, so, if you want to record a string, you need to jot down all the numbers, one by one, then upload the data into your Excel and then do the number crunching.
Which I do.
If that is what needs to be done to get solid information about the performance of a rifle, so be it.

I've learned recently that Caldwell has launched a new model that has BlueTooth communications so, I will try to get them to do the right thing (take this one back even for a nominal amount in exchange of the "new" one), IF they do, I will edit this article.

The Caldwell was supposed to be a "portable" device. The chrono itself works with a 9V battery, that can be a rechargeable one, and the IR screens, work with a 6V battery pack made up of 4 X AA's, that can also be rechargeable.
For a while, the portability and the capacity to record each shot as I was shooting groups proved to be a great asset. The occasional "flyer" could be discarded or confirmed. AND this takes us to

The present

So, when the communications between the phones and the Caldwell stopped working, I got again on the research train, and found not one, but TWO interesting solutions, so let's take what I consider to be the less effective first:

This is the Nate Chrony. It attaches directly to any barrel that has ½"-20 UNF muzzle thread, and if your barrel does not have a threaded muzzle, then there are adaptors available.
It is 3D printed and works, not with an App, but over WiFi, as a web-based "facility".
It is small:

And light.
You can attach it to the rifle and you really do not feel too much the added weight or mass.
It DOES have memory at the Web page level, and it has sufficient computing power to calculate averages, extreme spreads and standard deviations, you can store up to 4 strings, LONG strings. And it has the capabilities to graph the data.
It is a bit awkward that you cannot graph PAST data, but if you are ordered and systematic, you should not have a problem. Also the Standard Deviation is calculated as a population, when the correct statistical approach is to calculate it as a Sample Standard Deviation, which is what a string of shots is.
If you have other chronos that you need to interoperate with this one, it also has a "calibrating" function.

There are two things that it does not have and that, to me, make it less than useful:
1.- There is no way to "export" the data, nor the graph.
2.- It needs an external power source.
If your phone does not have AMPLE battery capacity to drive itself, the WiFi, and the Chrony, your chronoing sessions could be somewhat short.

The Nate Chrony offers a wide enough "channel" to make sure that it is not sensitive to smoke (from airguns dieseling during the initial shots), or debris in the field.

It would be ideal if it was not saddled by the need of the external power source. AND if it could export the data in an easy to operate manner (like a .CSV file).

And so, we come to the one that TO ME is the most useful:

This is the "Qiu Feng" (pronounced "Chiu Fang"). As you can see, it is also small and light.
Th body is an aluminum casting , closed by two aluminum "faces" that are screwed shut by two very long screws.
It has enough memory for up to 100 shots, and stores it in reverse order (so, shot #1 is really the last shot taken).
It works in both units (SAE and Metric), it stores the pellet weight, and calculates Muzzle Energy.
It has an App, that works well with phones that have Android 12 and newer.
The app can "tell/talk" the measurements to you, if you do not want to be constantly looking at the phone or tablet.
The internal battery will hold well for several sessions of chronoing.
It does NOT perform any calculations, nor can it export the data stored through the app.
It also allows you to "calibrate" the readings if you need to interoperate with other chronos.

So, if this one does not graph nor calculate, why is it the most useful?
To ME, the calculations are not useful if they are not done in a mathematically correct way, so I have to repeat the calculations anyway.
AND, if I am disciplined and take 10 shot strings at different bullseyes, I can map the results of the memory to the resulting target. That saves a ton of time when doing the write-ups.
The "channel" it offers is much narrower than the NateChrony's, so for those spring-piston airgunners be aware that smoke is opaque to IR (reason why the CO2 is a greenhouse gas), and that using the Qiu Feng in a spring-piston airgun may require cleaning BOTH screens from soot and hydrocarbon condensation:

This last issue caused me severe heart and head-ache, but I have to say that the two people on the other side of the Pacific that are in charge, took care, answered my EMails and tried their best to help me, without their help, I would have ended up deeply disliking the device, and all through my own fault of not recognizing that not all spring-piston airguns are completely devoid of some dieseling.

The "Qiu Feng" seems to have been designed for the air tube over the barrel rifles, you WILL need some washers that are ½" ID and 1 ¼" OD to properly space the chrono at your muzzle.

We've come a LONG way, Baby!

Over the years, the art and science of building better and more useful chronos has taken huge steps.
From the original Oehler 10:

To the 33:

And beyond.
We should be grateful that things have come down in size, weight and price.
Truly, the "golden age" is right now:

Keep well and shoot straight!

HM

1 Comment

"Mr. Hyde", or Full Power version of the Mauser K-98 S

3/26/2025

0 Comments

Disclaimer:
Modifications made to this rifle were performed by an experienced professional airgunsmith. And, proved safe in THIS gun.
No warranties are implied nor extended.
We have no control of what you do on your own.
If you do decide to make ANY modification to an airgun, be conscious of which elements are under force or pressure and realize that, even a "little pre-compression" or as little as 10 BAR's CAN cause SERIOUS bodily harm.
These modifications have not been reviewed, nor approved by DIANA / M&G
Again: Be careful! You are the only guardian of your health and safety.

Two "personalities" in one model

When the Scotsman, Robert Louis Stevenson, wrote the famous novel: "The Strange Case of Dr. Jekyll and Mr. Hyde", he was writing about a commonplace phenomenon of the Victorian Era.
Persons that were the very image of Gentleness and Propriety in Public, had an underlying strain of lust and bottled up violence that came out under the right circumstances.
In true Victorian fashion, at the time of writing, the novel was purported to portray the inner fight of the "good and evil" personae inside each one of us.
After reading other works by RLS, I have come to the conclusion that it was not that "inner fight" the one that the author was trying to portray, but the desire of the Victorians for more "raw" experiences. Raw in the sense of physical power, of getting things done.
Of course, this was also the time of the magazine/pamphlet/periodical "The Pearl" (you will have to look this one up yourself because it is not for polite company). Which would do the same for the love life of the Victorians.

AND; BTW, it didn't help that it was also the time of the "Jack the Ripper" crimes that never "got solved", probably because they were perpetrated by an "extremely high up personality".
Again the dual sides of getting rid of a problem (real or perceived) in the "proper" way, as opposed to the raw, direct and immediate "final solution".

Just "Food for thought" in our current times.

Now. Back to airguns:

Is power in a spring-piston airgun "evil" in itself?

Hmmmm . . . . Nope!

It all depends on the platform and the purpose.

In previous occasions I have mentioned that the laws and rules that came into effect in the UK of GB and NI in 1968-1969 were drafted by persons that actually knew something about pellets, airguns, and ballistics.
If you factor in the average pellet weight of the era and the MV's most conducive to proper stability, precision, and accuracy you will find that 12 ft-lbs is a REALLY good number.
Perhaps we should say "WAS".
Why? because in the last 57 years, the art and science of making pellets has taken large strides, and nowadays, the medium weight pellets (between 8 and 9½ grs in 0.177" / 4.5 mm's), can now travel excellently well at 875-900 fps, and that is about 14½ ft-lbs. Which, perhaps not unexpectedly, is the point where most AAFTA Open Piston and Hunter Piston shooters tune to.
Still, the International Version of FT clings to the 12 ft-lbs and that makes it an interesting game where marksmanship skills play an all important role. Yes, guns, and especially scopes, play an extremely important role, but at sub-12 ft-lbs, it is the marksmanship skills of each shooter what takes the day.

ALSO, nowadays we have "bigger" pellets. I remember when the JSB Exact "Heavies" came onto the market. They had a long "waist" to achieve the 10.3 grs. weight, The Crosman Premiers of the day, had an almost solid skirt, sealing at the head and just taking the skirt for the ride. These Premier (Heavies) scaled in at 10.5 and the Barakuda Match came in at 10.6 grs.
Later, the JSB H's went through a re-design that made them approach a slug because it has no real "waist". Rather the head and the mini-skirt are linked by a "column". Of course, the pellets themselves being a "flange (not flare) stabilized" projectile do not actually NEED the skirt (as a shuttlecock would).
The end result is a pellet that has VERY good ballistic characteristics when compared to other, more "traditionally made" pellets.
So, when I had the opportunity to make the companion K-98 S to the one described a few months ago, I opted for the "Mr Hyde" version of that Dr. Jekyll.
This one was NOT going to be demure, proper, "educated", or "gentlemanly" in any way. This was going to be a true "Valkyrie" in the sense that it would thrive in power.
And, in order to do THAT, and retain the precision and accuracy needed for our airgun games, we would have to come up with a slightly different architecture.
Last, but not least, we did not want to loose the personality of the K-98 as a "war implement".
If the first one had been the "low" power (still illegally powerful by UK stds.) was the "Auskundschafter" (Scout), this one was going to be the true "ScharfSchützen Gewehr".

After a few weeks of work, this is what we ended with, the left side:

As far as length, weight, balance, and overall "feel" this one feels just like the "real thing".
The grip, the shouldering, the LOS, the weight. With your eyes closed you would swear you are holding a vintage K-98 made in the late 1910's
On the right side the mystery is revealed:

There is no bolt. So, you're safe shooting this in your backyard. It MAY raise a few eyebrows, but . . . just be safe and courteous when the SWAT team arrives.

;-)

The Full Power Tune

For the ~12 ft-lbs version, we made an Ultra-Light Piston and calibrated the weight of the TopHat to JUST yield the 13 ft-lbs the owner desired.
For this one, a Mid-weight piston yielded initially well over 900 fps. And so, the Titan #1 had to be strain set and then, still doing about 900 fps, reduced by ¾ of a coil to manage a more stable and accurate velocity for the JSB H's:
Strings of 30 shots gave us these results:

If you do the calculations, these MV's put the K-98 S in the 18.5 ft-lbs. with the full length spring, 17.6 ft-lbs. with ¾'s coil lopped off, which is pretty much what I wanted.
Add a low sample Standard deviation and you can be confident that, as long as the barrel likes the pellets, it will be an accurate and precise combination. In graphic terms:

This type of power and stability is PCP territory.
With the exception that the shot string can be as long as the shooter's biceps and elbows hold, LOL!

In the previous version we did not need to get rid of any "lost volume", the weight of the TopHat was tailored to the power output, so there were no high pressure gases still behind the pellet when the pellet exited the muzzle.
In this case, we knew we had to solve an excess of air being pushed about because accelerating a 10.5 grs. pellet at 8,500 g's for the full 430 mm's of barrel travel would need a vortex diverter. AND, yes, this is a real number, if humans pass out at 7-8 g's, just imagine what 8,500 g's mean.
So taking advantage of the threaded muzzle of the K-98 S, we installed this:

Anyway, our pellets are so good that they do take that outlandish acceleration and fly to the target with some degree of controllability.
But the controllability increases if you make sure that the pellet flies through "calm air" as soon as it goes out of the muzzle. There are some "pundits" that maintain that the spin of the pellet is mostly needed to get across the "mushroom" of turbulence created when the pressurized gases exit and overtake the pellet in its path. While that is a partial truth, it is not the whole, sole, and unadulterated, truth. Recent productions of custom barrels with slow twists have shown that SOME spin is still beneficial.
On the side, I also use the location of the moveable brass weight to tune to some extent the harmonics of the barrel.
For reasons that should be obvious when you analyze the way the gun disassembles and (if you have not read the previous note, do so now, to understand how this barrel becomes an exercise in rigidity once the whole thing) is put together again, these are much lower than in other versions of the D 460 (of which the K-98 S is one variant), but it is still nice to have some degree of controllability in that.
Finally, as part of keeping in the character of the K-98, we needed some "battle sights". Which we found with the Tech sights for grooved receivers:

A detailed image:

Because we were planning to use this rifle with iron sights for some precision shooting, it was essential to have some sort of "peep" sight that would give us a long and low sight radius, which these sights achieved with great success.
The sight picture is quite clear:

The shooting

Now, why we were thinking about using iron sights?

Well, DIANA has made a commitment to support the Boerne Schützenfest. Last year I was unable to attend because it coincided with the FT Nationals; having been to a few over the years and over the world, I can tell you that they are a lot of fun.
Mostly because they are usually held as some part of an "Oktoberfest" (the agricultural harvest starts in September and ends in October), which of course, involves some good food, some good beer, and some good company.
Target is challenging, though it is not difficult to get a high score because the center is worth 25 points, and the black goes down to the 18. Missing the last "white" ring of 17 gives you zero points, but as long as you keep them all in the "black", you are doing good.
When the gun was tested with a reduced version of the target (for 10 meters), this was the result:

After the first "Cold Bore" shot, the remaining 10 shots went into a group smaller than a dime.
The K-98 amazes me in how "shootable" it is.
Further testing in true "match" fashion yielded good results.
This is with the iron sights:

It was the best card of the night's six, but it still shows that disciplined shooters can shoot well with "battle" irons.
Another session, this time testing with the 2-7 X 42 scope set at 3½X yielded TWO good cards (again, out of 6):

Why are the targets "pink"? because if they are black you cannot discern your hits . When they are printed in "pink" you can clearly see your impacts, even with iron sights.
Perhaps not quite as good as the first one (one point lower), but there were TWO in this session and that tells you that it is easier to be consistent with even a small scope, than it is to be consistent with "battle" irons.
Next test with the Schützen target will be with irons, but with an aperture up front (Korntunnel). And then we will see what happens. But that will be later and we'll use my Tyrolean D54 (of course, what else would be appropriate? ;-) )

Before I forget:
A note on the scope used:
It is made by Viiko

And it has a peculiar reticule:

A close-up of the reticle shows that, apart from the "rangefinding stadia wires", it also has POI drop marks:

It is a SFP variable, which will lend itself well to stadia-ranging. And we altered the parallax to 25 yards. Not complicated in simple scopes.
As the parallax was shortened so did the Eye Relief and, so, from an almost "pistol scope" eye relief it is now in the "High recoil" scope region. It can be mounted forward to have "situational awareness" at low mags, and also dialed up to provide precision and accuracy when the shot allows the time to do so. It would make quite an interesting hunting scope.
It is an inexpensive scope (which encourage customization) and the optics are good enough for some airgun uses.
The reticle gives me some ideas that I need to test, if those pan out, it may be a VERY interesting experience, LOL!
The Mount had to be "sculpted" to fit the rather large saddle and erector spring assemblies, but it is working well.

Now, would this be a good rifle for longer ranges?

Definitely YES!

This is how the rifle prints at 25 meters:

5 shots well under a dime and 10 shot groups under or at the dime o-o.

And beyond?

This is a 10 shot group at 55 yards / 50 meters:

Yes, there are 10 shots there. The stray shots on the left, outside the "Sighting" square, belong to other groups.
With a 7X scope and hold-off's, this is mighty rewarding in a windy day at DIFTA.

Would I use this setup for AAFTA Hunter?

I am seriously considering it.

MAYBE I would have to install a better scope, maybe a Veyron, or something like that. But the capabilities of the rifle are amply demonstrated.

AFAIK, there are no more K-98 S's on the retailers shelves, but the 460 is still in the lineup and perhaps there are some here and there in the warehouses.

While this one may be the Mr. Hyde impersonation of a raw and unpolished element. it is also true that the gun is a "wahre Walküre" ready to take to the action fields.

Keep well and shoot straight!

HM

0 Comments

Exploring the Steel-Spring'ed EMS powerplant

2/26/2025

0 Comments

Using a 34k in 0.20" cal

The EMS powerplant is a peculiar beast.

The result of extensive tests (thousands and thousands of shots taken), and the desire to make a dual power-plant rifle, it is a 7 part system (L to R in the picture below):

Piston
Forward guide
Spring
Shim
Rear guide
Piston skirt centering bell
Filler Screw

Now, being a 7 part system means TWO things:
1.- More manufacturing cost
2.- The need for more precision in the execution

For three years now, the "Motto" of the DIANA brand has been:
"Our Mission is Precision"

AND, as it is basically unavoidable, like all changes, it needs to start from within (remember the song "The Man in Mirror"?)

So, this exploration goes into what can be GAINED by using a steel spring in the D-34 sized break-barrels with the EMS architecture, and what needs to be changed.

Let's start with the diagram:

Numbers 1, 2, 3, and 4 are the basic mechanisms tube with the trigger block included.
Number 5 is the rear spring guide
Number 6 is a steel centering "bell" designed to hold the piston in the center when cocked, and allow the interference sear to do its job consistently.
Number 7 is a washer to protect the plastic rear guide from the steel spring
Number 8 is the screw that affixes the centering bell (# 6) to the trigger block (#2).
Number 9 is the spring itself
Number 10 is the front guide that telescopes into the rear guide
and Number 11 is the piston

Now, let us think about DIANA's "motto":
We have 7 pieces that need to align along an axis that is about a foot long (12"~~ 300 mm) and upon whose precision depends the consistency and efficiency of the powerplant.

¿Why?

Well, in a spring-piston powerplant there are several energy "sinkholes". The most important is friction, we take care of that mostly through lubrication. The next one in importance is "chatter", and that means all the small lateral movements that happen when a long thing vibrates along an expansion stroke.

How important is chatter?

Well, let's just say that IN THE SAME rifle-pellet-lubricant combination, a traditional D34 powerplant was able to yield about 13½ ft-lbs
Then, with the NTec unit (that prevented a lot of the chatter), yield went up to 16 ft-lbs.
With a "precisioneered" (precision engineered) EMS architecture it is now yielding 17 to 17½ ft-lbs
AND with a reduced cocking effort because Gas Springs will ALWAYS start from a very high force and go higher from there.

So, by reducing the tolerances and ensuring that everything is operating along the same axis, we gained a bit more than 25% yield with a reduction of about 20% in the cocking effort (and therefore the energy input into the system).

Yup! That is what true precision gains for us.

If you put it in numbers:

Efficiency of a traditional 34 PP.-
13.6 kg (30 #F, or 133.4 N) PCF over 135° of arc (2.36 Rads) on a 0.34 m radius.- Since the Compression starts from a value (preload), we will take that into account by an arbitrary/empirical factor of 0.6 (the average is a little more than ½ the peak) That means 64.22 Joules of energy input, vs. 17.6 J output, means an efficiency of about 27%

Efficiency of an Ntec equipped version:
20 kg (44 #F, or 196.2 N) PCF over the same arc and radius, means a peak input of 157 J, since the NTec starts from a substantially higher force, the factor now for the average force is about 0.7, instead of 0.6, so the input is 110.2 J, for an output of 21.7 J, that means an efficiency of 20%

Efficiency of the steel spring'ed EMS PP.- you need to input 18.2 kg (40 #F or 178.2 N)since this PP starts from a low value, we use again the 0.6 factor for the average vs the peak, and that means an input of 85.8 J, for an output of 24 J means an efficiency of 28%

Is this performance max'ed out for the 34 size? Yes. To get more/more efficiency, we would need to go the route of the fixed barrels.

Now, is there a way to achieve these gains without increasing the cost?

Well, yes, but it needs a change of thinking.

On one hand, parts #'s 5, 6, 7 and 8 can be "unitized" in a single piece made up with two different materials in three parts.
Could it be made as a single extrusion/molding? Perhaps. Modern moulding techniques do allow for "overmoulding", meaning that you mould a part, then insert that into another mould and the final injection takes place.

But what is a dramatic departure from the traditional method of manufacturing is that this "unitized" part would have to be made OVERSIZE, and then CNC machined to precise dimensions with small tolerances.

The frontal guide (#10) also needs a serious tightening of tolerances, especially at the front where it meets the piston. AND the fit between the OD of the "stem" of part #10 and the ID of the "Unitized" guide also needs serious tightening, as well as the fit between spring and guide.

I am now hearing all of you saying:"Precision in manufacturing is not the same as precision at the target

LOL!

Yes, that is true, and not only precision, but accuracy is also important. Theoreticians think that if you achieve precision, then accuracy is the "simple matter of adjusting the sights".
Alas, those shooters with experience know that this is an oversimplification.

What happens if the sights don't adjust consistently?
What happens if the sights are vulnerable to thermal differences?
What happens if the sights are simply not adequate to the target at hand?

Many of the problems are "solved" using a scope, but scopes have their own issues, especially in the field.

Still, the best procedure to test a rifle is by shooting it.

And, yes we did a ton of that, mainly because our scope suddenly started playing scope "games" on us. We would shoot a great group at some point in the target, then the next group would be elsewhere. The we shot a shotgun pattern that was not even a group!
Since that particular scope has been with me for a LONG time and never failed, AND that scope has been mounted in "accurized" ZR Mounts, that is the last point we suspected.
So, we tuned the bedding (after all, even the most "sophisticated 34 is still a 34.We tuned the Muzzle piece (an HPM Unit), and we tested different pellets.

The pellets were not the issue, the JSB's 13.7's were shooting as they should.
The bedding took a bit of experimenting, at this power level, minute differences have substantial effects.
After three days of testing (and two full pages like this), we decided something was wrong, this is what we were getting:

Yes there were some great groups, but... no consistency.
This is a good example:

Five shots vertically scattered, then a tight group, then another five horizontally scattered.

Now look at this:

Top row left to right:
A so-so group, then a better group, then a hideous group, then another good group with a lonely "flyer".

AND, we knew that it was not a question of oscillating MV's:

So, we decided to swap scopes.
Wonder of wonders, miracle of miracles! LOL!
This is what we got, straight off the bat:

This is the process of sighting in.

And when you click an inexpensive scope, you EXPECT to have to take one or two shots to settle it down.
Even some not so inexpensive scopes do this. Especially in a springer that is yielding almost twice its own weight in output energy.

At 25 yards, these are dime-sized groups from the knee and a scope @ 9X, let's validate that assertion:

Yes, I know there is one Canadian dime there, What do you want? I like the guys!

Want to see how the groups are totally covered?

I need to finish the sighting in, but that will come at a later date when there is less wind.

Is it easy to shoot a light and powerful break barrel? Nope!

It would make a heck of a hunting rifle, or perhaps Silhouette?. Short, light (9# WITH scope), and with a lot of KO power as far as pigeons, squirrels, grackles , rats, etc. are concerned.

So, there you have it. Power, precision and accuracy in one small, light package.

AH! before I forget, dry lubed. Absolutely no oils or greases in the compression section.

In short, precision at the target comes from "internal harmony", and "internal harmony" comes from the precision fit between the parts that make up the heart and soul of the airgun.

Same could be said of humans ¿no?

Keep well and shoot straight!

HM

0 Comments

Playing a little with a DIANA 58

2/6/2025

9 Comments

Re-sighting it really, LOL!

One of the pleasures of the professional airgunsmith is that, at times, someone, somewhere, finds something completely unusual and "out of this world", LOL!
This is one of those occasions.
A friend told me he had just acquired "an old DIANA", and that he wanted me to have a "looksie".
Well, we met at our Monday Night shoots and I was taken aback when the old dame came out of the case.
A REALLY OLD DIANA!
I thought to myself: "this is probably the first model to come out with a forearm in the stock"
Well, it seems I was not too off the mark.
After all the admiration, my friend told me that the gun was shooting to the right and up, he had to aim at the lower left corner of the target to hit the bullseye.
Hmmmm, that's not good.
Further, he told me that the sights had no way of adjusting the windage. Hmmmmmm
So, after looking in detail at the rifle, it was clear that the design intention had been to drift the sights to set the windage. The blade had a way to elevate, though a bit primitive, it was used all the way into the year 2k in the DIANA 30 (the shooting gallery/Kermesse gun).
So, that's where that peculiar sight came from!
After a few more words were exchanged, we concentrated on the task at hand (shoot 60 "for score" shots) and once that was done, we all had a long session of shooting the breeze.

When I got home, I put away the gun and during the week, in one of those instants where it seems time has stopped because you are waiting for materials, parts, tools, or "all of the above" to arrive I decided to tackle the "simple" job of re-sighting in the old lady.

In the light of the workshop, daytime, and more awake, I came to realize that for a gun that old it was in amazing state of preservation. Bluing, wood finish, everything was almost pristine.

BUT! Enough words, let's take a look at some pictures:

The DIANA 58 in all its splendor

Which is vastly superior to what they offered in the catalog:

There are some small differences, like the ring front sight that is not in the actual sample, and the "handle" of the cocking lever that disappeared, but apart from that it is a proper incarnation of the line drawing.
The "branding" in those days was a bit "Spartan" (or should we say "Laconic"?):

No model, no manufacturer, no origin.
Still, simple, elegant, and very clearly legible.
BTW, the rifle has NO OTHER markings.

This is the rear sight:

As you can clearly see the dovetail allows for some drifting and the elevation blade runs on the head of the screw. Not a "micrometer visier" but quite serviceable.
There are range markings on the side of this sight (10 to 50, I assume, meters), though not particularly exact/correct, it is a tribute to how something simple can still be effective.
And this is the front sight:

Again "driftable" in the dovetail.

After a few test targets and some measurements, the results were quite satisfactoyry and I had time to admire the craftsmanship that went into this rifle. Let's look into it in some detail:

This is where the cocking lever connects to the linkage.
The main screw has a "fixation" screw that can lock the position of the screw every ½ turn. And we need to assume that the axle screw is a "Shoulder screw". Nowadays, the same job is performed by a pin, with or without a head, and one or two E-Clips.
Now, let's move forward a little. This is the lever:

And, if we look at it in detail, we see that it was milled, and even checkered, from solid:

Now let's move back and see how the lever/linkage arrangement gets connected to the mechanisms tube AND at the same time serves as a mounting platform for the tap to load the pellets:

Also note above the distance markings of the rear sight.

In the purest sense of the word in gunsmithing, THIS would be the "receiver ring" because at the front, it receives the barrel and the rear, receives the power source.

Now, we go all the way to the back of the mechanics and we find this:

A cocking knob!

That cocked looks like this:

Because, after you have cocked the spring, and inserted the pellet into the tap, you still have to cock the hammer that strikes the sear that releases the spring.
Safety? Or a simple solution to holding about 200 # of force and releasing them with a gentle trigger squeeze?
¿Both?
We'll never know. It makes the loading cycle complicated, but safe and the trigger pull more than manageable for some precision shooting.

If we go to the stock now and look at the forend:

We find finely grained walnut, well sculpted for the purpose (this is one of those guns where the artillery hold is absolutely indispensable!
And screw cups! If anyone thought it was a modern invention, here is the proof that in the world of guns, there is VERY LITTLE that is truly original and new.

AND, what can we say about the pistol grip?
Extremely "English" in its conception and execution:

Rounded heel, flattened diamonds, double borderline. This pistol grip would be perfectly at home in any high end English Side X Side of the times.

The one "problematic" are this rifle has is where someone (surely an American), decided to use a "tang sight" to shoot longer ranges with more precision than the OEM sights allowed:

According to my measurements, these holes can receive exactly the base of a Sharps/Borchardt long range rifle.
Still available, it is not out of the question to get the bases and then add a mid-range sight that would allow the shooter to shoot out to 65-75 yards.
Since the rifle is a 5.5 mm's ("number 2 bore" per the English nomenclature of the time) / 0.22" it is capable of reaching the 55 yards with enough authority to drop the Rams.

Going all the way to the back, the buttplate is a steel plate:

And again the complete gun:

Shooting a round of 10M MMS (Mexican Metallic Silhouettes), I achieved a 32/40, not a stellar score, and just slightly under the score I would have shot with the K98 S but then the K98 S easily has one of the best sets of notch and bead iron sights in modern airguns ever, and that includes the FWB Sport of modern times.

Point is that the gun is now shooting to POA without any need to do anything to the barrel and using fairly inexpensive Crosman Copperhead Pointed pellets and more reliable/consistent JSB's Express.

All in all a VERY enjoyable excursion through a time machine.

Would it be possible to make an airgun like this today?

Yes, issue here is :
Would anyone buy it at the cost it would imply?

Just taking a SWAG of what a gun like this would cost today: It would run north of $2,500 MSRP. Even using modern CNC machinery and current metals.

Hope you have enjoyed the pictures as much as I enjoyed having that old lady for a short while.

Keep well and shoot straight!

HM

9 Comments

The Hämmerli Pneuma

1/14/2025

2 Comments

Disclaimer:
Modifications made to this rifle were performed by an experienced professional airgunsmith. And, proved safe in THIS gun.
No warranties are implied nor extended.
We have no control of what you do on your own.
If you do decide to make ANY modification to a PCP, be conscious of which elements are under pressure and realize that, even 10 BAR's CAN cause SERIOUS bodily harm.
These modifications have not been reviewed, nor approved by Hatsan or Walther/Hämmerli
Again: Be careful! You are the only guardian of your health and safety.

Phewwwwww!

OK, now with the "small print" done, let's get down to our matter.

What is, exactly a "Hämmerli Pneuma"?

The short answer is that a Hämmerli Pneuma is just a re-branded Hatsan AT44

The long answer is that, for ME, there is NOTHING of "Hämmerli" in this rifle, and to get what I mean by this, we have to go back more than just a few decades.
Many years ago (58, to be precise), I had the luck to see my first Match rifle.
Walking to my nearest "Sears Roebuck de México SA de RL y CV" (the Mexican Version of the company), I was regaled with the sight of the most beautiful rifle I had ever seen.
It was a Hämmerli Mod 45 Free Rifle.
Priced at the, then, EXORBITANT cost of Mx$3,595 (1966's US$ 287 ) it was way beyond the wildest dreams of a 10 years old.
Something like this:

Years later, I would come to own an Anschütz Match 64, and a Tanner Free 300 M, plus a Steyr SSG '69. But I can certainly say that my love affair with precision target rifles was born at the old "Sears" in Mexico City.

Therefore I always had a soft spot for the brand.

When UMAREX purchased Walther and Hämmerli I was dismayed.

What was going to happen?

Well, now, even that is history.

Luckily for Walther, the "Match" branch was spun off as an independent unit and they still produce top notch airguns, The Firearms branch is also independent, having been set apart from the UMAREX deal.
The Walther "Sport" branch of the airgun business produced two of the most advanced spring-piston airguns in history, only to die a quick death with the sale of all the parts and stock of what remained of the Walther Century Varmint parts to UMAREX for the creation of their 3400 model.

On its side, the Hämmerli brand has graced products made in China, Turkey and Mexico. Products that whether spring-piston or PCP power plant, have little to do with the Precision Match rifles of yesteryear.

Nowadays, through the German connection (Hämmerli was a SWISS company), they are re-branding the ISSC SPA "toggle bolt" RF as the Hämmerli Sport, and that is a gun that MAY be worthy of the brand, if the quality of the barrels honor the precision they promise. It should be noted that it is the THIRD "re-birth" of this particular RF.
BUT, we're getting away from the "Pneuma"

And here we arrive at the short answer: when UMAREX wanted a Hämmerli branded PCP that would get some traction in the "Sport" section of PCP airguns (they had already developed the Match version of their bottom of the line Walther into a passable beginner Match gun) they picked Hatsan, and the Pneuma is the result of re-branding a Hatsan AT-44.

The AT-44 has in itself, gone through at least two versions, the original one that we will call the "old model", and the new one that is sold under the "H" spec.
When Hämmerli discontinued the Pneuma, Hatsan advanced with the "H" version and the way the tanks hold the valve changed a little. This will be important later on.

Soooooooo....

When a very good friend of mine asked me if I would take a look at his son's airgun, I replied that it all depended on the gun, I asked what needed to be looked into, and he commented that they could not get more than 20 shots out of a full tank fill and that they wanted to have the gun regulated, so that they could plink in a more comfy environment where the gun didn't need constant re-airing.

I answered that, subject to the availability of spare parts and accessories, I would be glad.

The Project

Everything started then at one of our Monday night shoots where, and when, I received a huge case with a smallish PCP.
I checked it over and wondered exactly what had I gotten myself into. LOL!

Some online research clarified to me that it was a Hatsan. Checked with my friends at Altaros (best regulators out there), and they DID have a regulator for the Hatsan. The only issue was winter holiday season in Europe was starting and all means of transportation were getting overloaded.
I still decided to order one because that would be the "gold standard" by which to judge other options.

Almost at the same time, I found the Hatsan made regulators and some looking into the old Youtube videos provided some interesting information:
a) there were two types of valves at the tanks. One that uses a simple plastic plug to hold the valve return spring (what we call the old model), and another (H type) that actually has a plastic screw in perforated plate that holds a much stronger return spring.
b) the inside finish of the tanks had gone down over the years. The older tanks were much more even and smoother
c) the regulator for the older model had a relatively small "plenum", which would limit the tuning options
So, I ordered a new tank under the new "H" spec and ordered two "H" regulators.
d) what I liked a LOT, was that the valve was IN THE TANK.

When the regulators arrived, to my dislike, it turned out that the newer "H" regulators were non-vented.

I generally like vented regulators for all guns, the non-vented regulators have a tendency to "creep" and even if it is well made enough that they do not "creep", the first shot is always low.
In a hunting scenario this will surely cause a problem, either a miss or, worse, a bad hit that will not cause immediate death. That is, ethically, unacceptable and should be avoided.
So, some non-vented regulators do require one to three "evening out" shots prior to actually starting the hunt, and then, the hunter should know how long the reg can stay under working conditions.
Not hard to determine, but something that needs to be determined BEFORE.

In view of that condition, and after studying what we had at hand, I decided to modify one of the "H" regulators to be a vented one.

They may look the same (well, almost), but the working is a bit different.
Let's see them from the front:

On the left is the vented one, on the right the OEM one.
observe where the "dimple" has been lathe turned in the center.
And now, let's look at the OEM one's attachment method:

As you can see, the valve return spring is held in place and pre-compressed by the regulator's front end.

It is not a bad system "per se", but it goes contrary to my philosophy as far as poppet valve tuning is concerned because I believe that MOST of the closing force for the valve has to be provided by (ideally) the flow speed, and if that is not possible, then the pressure remaining in the plenum or tank.
This is a "passive" way to ensure that the valve will self adjust to the natural lowering of the pressure as shots are taken.
But, that is JMHO. YMMV.

The other difference is the location of the additional ORing.

If you look at the vented version, you will see that it has an additional ORing at the rear, where the regulator's body meets the plenum chamber.

Well, that ORing makes it possible to remove the tank's closure ORing and create a vented reg. BUT, this works MUCH better in the older tanks that had a great finish and therefore needed little inteference for the ORing to seal at the rear. In the newer tanks, a bigger ORing is needed and this creates an unsafe situtation where you MAY think the tank is empty, but there is still pressure in the plenum. SO, BE CAREFUL!

ALTAROS regulators have a great site and their installation has been well documented, so we will not go there.
Suffice to say that ALTAROS regulators are graduated and offer a much better option when you want to tune an airgun to some specific specs and not just "dialing it to 11".

Now that the machining part was done, the "fun" could begin. And I am putting " " on fun because it is a necessary evil to test long strings when tuning a PCP. Otherwise, you are just making assumptions about how the regulated gun is going to behave. Professionals do not do that. Simple.

With the two tanks in hand, a probe and a compressor, we started the tuning process itself, which will not be without its thrills and surprises, LOL!

The tuning process

Regulators were (at least that is what the purchase specs said) set at the factory to 120 BAR's
Now, that is, in truth, a VERY HIGH setting. If the gun needs 120 BAR's to yield decent MV's with a mid-heavy 0.22" pellet, then there is something wrong with the system's design.
It is not a bad setting if you are planning on slugs (which we tested), or pellets in the heavy for caliber region, but for mid-weight pellets it is a wasteful setting.

Anyway, that is what the factory sets them at, and there is no scale in the OEM regulators. On top: there is only ONE manometer in the gun, so that you cannot "monitor" the regulated cavity's pressure.
Your only method of determining what is the Reg'ed pressure is to shoot a whole string and note where the MV drops like a rock.
Following that method will also yield good information about the internals of the system and whether they are "balanced" or not.

Seven years ago, when we were studying the upgrade packages of the Stormrider, this was one of my main priorities; now it is almost a given in MANY PCP's, back then it was revolutionary.
So, with assembled and aired up tanks, we started the testing.
We had PREVIOUSLY, performed a few "benchmark" tests, which yielded VERY poor performances.
This is the OEM non-regulated setting:

The first indication that something is not right comes from the fact that the MV drops DOWN continuously from the first shot.
Yes, there is a lot of power in those 18 shots that are "really good" , but then, most pellets will not stabilize well from most barrels at this MV, so ¿Why use it? ¿Marketing, probably?
Whatever the reason, this was the source of dis-satisfaction about the rifle that my friend and his son had.
Quite understandable.
So, I thought, maybe they drew the spec for heavy pellets and slugs?
Well, here is the result of testing:

Not exactly stellar performance, and those two consecutive low shots with the JSB H's (10.3 grs) showed that there was something fishy going on in there.
The K-O slugs (same weight) performed well and more consistently, so there COULD be an argument made that the idea was to use slugs, but then, something does not "jive" in the balance of the system because the system is rated at 200 BAR's and, theoretically, at least, there are shots that could be taken at higher pressure and use the valve-lock to control the energy output.
So, what went funky in the design and prototyping? the spec of the tank's max pressure?, or the springs in the valving?
Because in principle I wasn't going to spend too much time in this project, I thought, well, we reduce the reg pressure and we'll be fine.
Customer had expressed the desire of 60 shots at 600 fps to make this a "plinker", so there were no real high stakes and just a lower reg pressure should do it ¿right?
Hmmmm, not so. This is the string of a regulated string with the vented modified reg:

Still too high an MV, way beyond useful, though consistency was good.
So we reduced the pressure in the reg to ABOUT 90 BAR's:

At first I tought I had done something wrong, probably "broken" the reg by setting it too low, nowhere could I find any spec telling me what was the min pressure of the reg.
So I tested with the Altaros at 100 BAR

WHAAAT????
We're getting less shots from a lower pressure regulated cavity?
As Hamlet would say: "Something is rotten in Denmark".
But this told us that the problem lied in the action itself.
The action was being wasteful, and there was no further adjustment possible to the valving.

But before that, we need to discuss the hammer adjustment procedure.
And, on purpose, I am not going to show any pictures.
All the videos and literature out there said that, to adjust the hammer strike you needed to put a long 4 mm's hex wrench through the rear hole and screw IN for less energy, OUT for more.
SOME videos told the user to cock the hammer, or to at least bring it back to where the screw was accessible to the wrench.
Well, at least in THIS version, that is total hogwash.
Even under hammer spring pressure the very long grub screw at the bottom of the hammer will make the hammer spin and not "take" any adjustment.
HOWEVER, looking at the bottom of the action, there is a nice little hole a little bit to the rear of the middle stock screw, and through that hole, when the hammer is partially retracted, you can LOCK the hammer rotation by inserting a punch through a corresponding hole in the hammer itself and effect some real adjustments to the power screw.
And so, we tried to reduce the energy of the hammer strike, only to find that it was at its LOWEST.

The grub screw at the bottom of the spring cavity in the hammer dictates the preload of the hammer spring, if it is out, there will be more pre-load, if it is in, there will be less pre-load.
At its lowest setting, the grub screw still protrudes almost 10 mm's into the hammer spring cavity, so this was dictating a LOT of pre-load.

As hard as it seemed, we had to get INTO the action.

The action seems to have been designed by a shotgun gunsmith.
The components are not actually "unitized" and springs are held by the pins that keep the trigger in the action.
Take out the pins to remove the trigger and there are springs that are now axle-less and can be displaced to places where they do not do their job anymore.
AND there is no documentation of how the trigger works.
So let's look at it briefly.
The trigger parts are not that different from all the airgun trigger parts we've seen that seem to stem from the Chinese Crossbow triggers of the 3rd Century BCE.

When the trigger adjustment screws push the lower lever, the front of this moves up and the rear drops down, thereby enabling the rear lever to rotate to the left, allowing the sear's rear to move up and the front down, thereby releasing the hammer from its cocked position.
It IS a good trigger, crisp and clean.
It is also an interference trigger, as opposed to hook triggers, interference triggers are faster.
Why give the trigger blade a counterweight? I assume it is mostly a place to put the first stage spring, though the weight does give the blade a little return force, it is not the determinant force.
Now, springs coming out of their place when disassembling something is not an unknown aspect of airgunsmithing, and the same solution that applies to spring-piston airguns applies here:
Dumb pins.
A dumb pin is a shortened pin that holds the parts of subassemblies in place while the assembly of the whole gun is being completed.
Once all the sub-assemblies are in place, the final pins drive the dumb pins out, the gun is secured and can be mounted in the stock and shipped.

So we turned two dumb pins, 3 mm's OD, 10 mm's long and they worked well.

One dumb pin is installed, the other is out for illustration purposes. With this sub-assembly in place, the action can be dis-assembled and re-assembled again as needed.

For our purposes then the action had to be dis-assembled, the grub screw adjusted to it MINIMUM, and then the whole thing had to go into testing again.

And this is exactly what happened, the grub screw was cut IN HALF, and the gun re-assembled for testing.
Once the power adjustment screw was cut in half these are the results using the Altaros regulator at 100 BAR's in the old tank:

NOW, we're cooking!
57 shots at top speed for mid-weight pellets is a good performance, sample standard deviation of 3.2 fps tells us that 95% of the shots will be between 911.8 and 902.2 which is perfectly acceptable.
If the user can find a pellet that is really accurate out of this barrel, he could shoot most FT matches without worried of refilling during the match. Make sure you start with a full tank, take two shots just before startin the match, and just keep on shooting!
For a light gun, this is perfectly acceptable performance, and, at more than DOUBLE the OEM performance, it was a good point to stop this avenue of development.

Now, the user wanted a "plinker", something in the 600 fps region.
There are MANY reasons why users may want lower power.
Noise
Neighbors
Backstops
Targets
etc.
So we decided to dedicate the Hatsan H tank and the non-vented regulator to reach that goal.
We tried setting the reg at "about" 70 BAR, and upon testing a whole string we observed something VERY interesting:
When the tank's pressure was at about 60 BAR's the valve self regulated!
This was a Eureka moment and we proceeded to adjust even further the OEM H regulator and perform a test.
Because we did know what happened at higher pressures, we started at 150 BAR's:

So, 78 really good shots using 2/3'rds of the tanks capacity, with an ES of about 19, and a sample standard deviation of 6½ fps.
NOT BAD.
DO note that even starting at a lower than Max rated pressure, the first two shots are "penalized" by the non-venting regulator.
Since the express purpose of this tank is to be a plinker, I considered the project had achieved its goals.
As a plinker and using the full capacity of the tank, this combination will yield about 150 perfectly usable shots.
Which means 1 shot per BAR.

Epilogue

As I said to my friend: Now you have TWO rifles.

It's a question of finding a pellet that works for each power level and having two scopes.

If you want to plink, you use the plinking tank and the corresponding scope and get a ton of shots without refilling. IF you want to pump by hand, then do not worry about going much higher than 170 BAR's and you will still get more than 100 shots.

If you want to get more serious, get the appropriate pellets and scope and you still get almost 60 shots per fill at 15 ft-lbs. Plenty of power for the caliber.

Overall, I would say it was successful project.

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

HM

2 Comments

<<Previous

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.
2015 Maine State Champion WFTF Piston
2015 Massachusetts State Champion WFTF Piston
2015 New York State Champion WFTF Piston
2015 US National WFTF Piston 2nd Place
2016 Canadian WFTF Piston Champion
2016 Pyramyd Air Cup WFTF Piston 1st Place
2017 US Nationals Open Piston 3rd Place
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
2022 Maryland State Champion WFTF
2022 WFTC's Italy Member of TEAM USA 2nd place Springers
2022 WFTC's Italy
2nd Place Veteran Springers
2023 WFTC's South Africa Member TEAM USA 1st place Springers
2023 WFTC's South Africa
2nd Place Veteran Springers