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

9/29/2020

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:

It seemed that the barrel really liked Pledge as a lube, so we tested different pellets:

But again, at 40 yards the whole thing fell through.
And so I decided to test something else, the harmonics tuner:

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:

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:

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:

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:

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

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The Gunsmith's Tune; Part 1/4.- Full Power Walther LGV

9/8/2020

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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.

UUffff! LOL! OK, so that is out of the way.

Let's go back almost a year to the last Pyramyd Air Cup.
Back then a good friend asked me: "OK, if you REALLY wanted to do something for YOURSELF, what would it be? Forget DIANA, field is open to ANYTHING, no limits. What would it be?"

I gave him the standard answer: "I am perfectly happy with my D54's, there is nothing I cannot shoot with either of the two (I was obviously referring to the full power 0.20" cal and the WFTF 0.177")

He took it in good stride and we parted, as usual, thinking that we would meet again in Ohio next year.

Next year came and, with it, an unexpected upending of ALL our way of life. No more FT matches. No more socialization in close proximity.
I barely made it back to the US from GERMANY, one day before all borders were closed, IWA was cancelled.
I did get to go to Puerto RIco, but that was the last big Match I shot in 2020, and only last week did we have a match at DIFTA.

But the conversation stuck in the back of my brain (what I call the back-burner), and suddenly, as we have been working hard in a long series of articles about recoil and harmonics with a really serious scientist, I found myself missing my ABP-LGV
As luck would have it, a used LGV popped up in the classifieds and at a very good price, so I placed an offer and the owner took it up, money was sent and rifle arrived.
From the description, I knew it was a shooter, not a safe-queen.

But that was what I needed.

As part of a long study process to tackle the tune of a FWB Sport (and then compare it to a Jan Kramer tuned FWB 124 of 30 years ago), I had decided to do some serious maths about springs.

And, looking over the stats of existing springs, I found some very interesting possibilities.

It also happened that Eric P sent me a version of his "curved trigger" for the LGU/LGV and I was absolutely delighted with the shape, but had no gun to mount it onto!.

So, when this shooter came up, I seized the opportunity. And I am glad I did.

The barrel was superbly dirty and leaded, but once cleaned, it proved to be an early and extremely well made specimen of the Walther factory.

AND it was threaded!

So, following the patterns established for the AM03 Compact we used as a base for the "Night Hunter" I made a front end for the LGV without any real intention to moderate it, as the end-goal is to compare this one with the ABP-LGV that is "on loan" and so, after this first chapter is done, I will probably tone it down to WFTF levels to see how they really compare. But that is in the future, where we will also look into the Gunsmith's versions of the 430L that builds on the success of the short-piston/long stroke concept.

I will not post detailed pictures of the gun, or how it was disassembled and how the tune was done, we have talked about that enough in other entries, so, if someone has not read them; please look into them:

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-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

https://www.ctcustomairguns.com/hectors-airgun-blog/new-super-custom-trigger-for-the-walther-lgulgv

I have always been a fan of Titan XS springs. They are of good quality material, they are reliable in their dimensions, they have proven to me, beyond doubt, to be some of the best springs in the industry. AND they do offer characteristics that are somewhat "heterodox" but very useful, as we will see.

The first aspect is that they offer larger than "normal", whatever that is for each of us, OD's for their springs.
Since stress in the material goes down with the cube (third power) of the OD, any increase in the OD is highly useful in the longevity of the spring, and that translates into many more shots at the same power level, which makes for enhanced reliability in the accuracy of the gun in question.

The down-side is that they do require carefully turned guides and the use of an "outside" guide, or piston liner is precluded.
Titan springs do not need it.
From the factory, they come covered in some slick, flexible, finish over the shot-peened metal that neither becomes brittle, nor flakes, nor chips. It is slippery and therefore there is no need for any further surface interface between piston's inside wall and spring.

Guides also need to be a little on the "hard" side. The softer grades of Delrin or other plastics will not do well.

Between the spring's finish and a hard-plastic guide, Ultimox creates the best possible riding medium. The use of VERY sparse lubricant in the spring makes it easy to accomplish the goal of the gun being an AIRgun. In the sense that no lubes are consumed to contribute to the power output.
Very little lubricant also gives the gun more consistency in the performance under different temperatures and ambient conditions.Hot or cold, these guns will perform in a reasonably consistent manner.

But I am sure most of you will be wanting some pictures, so, here are just a few, and I beg your forgiveness because I cannot divulge too much technical information, and I am not a really good photographer, anyway, LOL!

As you can see, the front end just adds about 3" of length and the gun is still compact. With the Bushnell Nitro FFP "Deploy" scope, it is rear heavy. Maybe I will change the CF tube to a thin steel one just to have a balanced rifle, but the truth is that it shoots so well that, apart from the power adjustment needed for international competition, I don't think I want to do much more.
I may, also use a different buttpad, a more "curved" one because a rear-heavy gun CAN be an asset in FT, as long as you ensure absolute consistency in shoulder placement.

The Bushnell Nitro is one of those cases where the logic behind optical equipment factories' commercial practices is hard to understand.
It was barely presented to the market . . . when it was discontinued! Only to reappear at 50% more money.
¿¡!?
I bought this one in a close-out at a very nice price (under $400), and have been quite impressed with the median-price range scope. In many ways it performs like a much higher priced glass, but in some others, it really is an inexpensive scope. Don't know that it is worth the new price (a bit under $700) to each his own.

As all of you that own Walthers know, the dovetails cut into the mechanisms tube is rather shallow, so an Accurized ZR mount was used to relieve the parts from the stress of the recoil and the need to use super-stout mounts that then run the risk of deforming the tube itself if too much torque is applied.

The leather cheekpiece has become a standard in the CCA guns, as it is real nice and there are left and right handed versions. In an ambi stock that lets everyone know that the owner has made the gun "his/hers".

AND (a VERY important "and") the trigger is the excellent "curved" trigger from Eric P as has been mentioned above that allows to be adjusted to break in a really set-back position so that, when using a sporter stock, there is no reason to "pull" the trigger. Just gently squeeze across the pistol grip.

Now, going to the power plant, it is important to mention that this is no tune for the faint of heart.

We start with a #1 Titan XS spring, then we create a guide that fits all the parts and "ties the system down"; on the rear end, the LGV trigger block arrangement needs one dimension, the guide itself is much wider to accommodate the Titan XS spring, so the "dual diameter guide" keeps the thrust washer captive between trigger housing and guide shoulder, on the front, the guide is fat enough that it can be "screwed" onto the spring, but it will not come out without twisting.
It also creates a HUGE PRE-LOAD (64 mm's):

So, you'ld better have a well made spring compressor because this cannot go in by hand alone.

Now, why is that important?

After my experiences converting my D34 to NTec, and then the AM03 (a native NTec gun) into a steel spring with an ABP, I noted that the NTec guns yielded a LOT more energy than the non-NTec guns (as in 16 vs 12 ft-lbs), and that getting the sharp, non-bouncy, shot cycle of the gas spring was something to be achieved.
The obvious way was with an ABP, but ABP's are complicated and expensive, so what other characteristics of the NTec were we overlooking?
The huge STARTING FORCE!

So, this realization was one of the reasons why I decided to start this project.

By having a large "at rest" force in the piston, it prevents a too big bounce-back (specially if no lube is burned), and so it is a more efficient duty cycle.
The disadvantage is that it stresses the spring to the limit. It starts from a semi-compressed condition and then goes to almost a solid. That is a heavy duty cycle for a spring. . . unless . . . it is of a larger than normal OD, AND it is made of the best possible material. ;-)

We also used our technique of using a very tight-fitting top-hat, and once everything was assembled, it became, actually, one piece:

Look, Ma!!!!! It FLOATS! ROFL! Trigger, spring, guide, and piston make one "unit".

Another interesting result, is that, by using more turns (therefore a longer spring), but of moderate wire diameter, the cocking is VERY SMOOTH, and the cocking force is very low, not more than the normal Walther spring.

After more than a few hundred rounds, the seal is almost as good as new, as opposed to severely "oversprung" LGV's I have seen in the past:

On the left is the "Gunsmith's Tune" seal, on the right is the result of a severely oversprung rifle. As you can see, the force of the secondary impacts has created dimples in the face of the seal.

OK, enough presentation! how about some stats? LOL!

Well, the gun yields between 14.6 and 16.9 ft-lbs depending on the pellet:

Baracuda Hunter Extremes exit the muzzle at 16.9 ft-lbs. (really good hunting setup out to 35 yards)
QYS Streamlined's zoom out at 14.3 ft-lbs. (FT capable)
Baracuda FT's at 16 ft-lbs (so, so, but Hunting accurate)
JSB Exacts at 14.9 ft=lbs. (reasonably good, but not quite as good as QYS's)

Here are few of the MANY target cards shot:

Pre-Tune benchmark. Good energy, but twangy and buzzy.

Post tune of the best shooting pellet (QYS). Notice that, apart from one shot I probably pulled, this gun is shooting to Match gun standards, but at 3 times the energy.

A first pass at Long Range tests (37 meters / 40 yards). QYS is still the best shooting pellet, and BHE shoot good, but are somewhat wind sensitive. By the end of the session, the Tunable MW was loose, so we quit till the next morning.

Next morning, with some wind, and after some warm-up, sighting in, and wind reading exercises, the 10 shot group on the upper left was shot at 35 meters/38 yards, then I backed out and shot the 5 shot 50 m/55 yards group. Drop between 35 and 50 meters is 1.25 mrads

All in all, some very rewarding results!

I know that IF I was to keep this gun at the present power level for hunting, pesting, and/or AAFTA/Hunter Piston FT, I could arrive at an intermediate tune of the Harmonics Tuner to be able to use either the BHE or the BFT, as required by the task at hand, with pretty similar results, since their weight and internal ballistics shape is pretty similar.

The excellent WEIGHTED BC (0.019 over all the distances to 50 m / 55 yds) of the QYS at such high speeds (879 fps), also points to the good possibility of having a SUPERB FT gun at WFTF levels.
Something we will look into in the next few weeks.

Lastly, the other objective of this exercise was to confirm the maths that govern spring behaviour with a view towards creating a special spring for the 430L, also useful in the 280.

Next we will explore the LGV at reduced power, the MAIN question here is IF the remainder pre-load will be enough to keep the good results while making the gun "legal" for WFTF, OR if at those low power levels the ABP is the better way to go.

So, stay tuned, 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.
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

Hector's Airgun Blog

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

The Gunsmith's Tune; Part 1/4.- Full Power Walther LGV

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