ammo speed

[spektr]

Gentlemen..... Please allow me a bit of latitude here.

The question isn't or shouldn't be "Does a tuner work".

The real question is CAN YOU MEASURE THE IMPROVEMENT.

Benchrest shooters do not struggle with "hold" or the physiological stuff like breathing and heart rate. They can measure the difference.

I deeply suspect that at the ranges position rifles are shot, human motion inserts too much noise into the problem for a good measurement to be made. Heres why.

Lets take vertical dispersion first. For sake of argument, lets assume a tuned barrel shoots exactly to point of aim.

A tuned barell held motionless will shoot everything in a single hole.
But we move around a bit, so a tuned barell will shoot everything to the center of a bell curve with the high point of the curve representing the displacement from zero. If the high point was 150 thou from zero, they all will miss that far. An untuned barell shooting with the center of the bell curve 150 thou off zero will sometimes shoot BETTER than the tuned barell AND sometimes worse, depending on the standard deviation of that particular slug of metal.

Since this is a randomised effect, and since hold is exceptionally difficult to repeat, the data is probably never clean enough to make a proof possible. There is also the small matter of a statistically valid sample size.
You wont find the answer in a human hold.

You WILL find the answer if you machine rest the gun to set a tuner to the barell, but the guns are already shooting in excess of the required accuracy to shoot possibles. Tuners will make it easier to get more rifles to shoot possibles and as an armorers tool, I expect to see more of it....

[dontshootcritters]

Thanks to all who have contributed to my slightly wandering post.The other thing to consider here for me is that we shoot indoor in New Zealand in the winter.25 metres only so no wind deviation to contend with so possibly not worth the added expense apart from extending barrel length to improve sight picture?
How ever I would be interested in hearing from Eric and Guy[has posted] about their thoughts.The other point is that Id be interested in how many rounds it took to find the sweet spot.For thos of us that don't buy cases of ammo it can chew a lot of rounds find that optimum setting.

Thanks again

[tenring]

1. A tuner improves the vertical dispersant. With a tuned rifle I have found the wind affects it less too. Maybe not less but affects it more consistently.

2. You will go through ammo. If you change lots you might have to re-tune. At first I'd go through 4-5 boxes to find it. Now usually no more than two boxes. And usually only one box. I have a method now that is different than Eric's and it saves me lots of ammo.

There can be multiple sweet spots, but once you actually find the "sweet" spot. You may never need to change it. Some will argue that, but with my tuned 2013 Anschutz it will shoot anything pretty well. I'm fortunate my cheap practice ammo has the same tuner setting as my match ammo.

I'd suggest once you get it tuned, have as much ammo on hand as you can in the same lot.

tenring

[Albert T]

This is a question fot Guy Starik,
Guy, in your oppinion can tuning a rifle instead of a tuner be done by changing the torque of the bedding bolts in for example 1/10th or 5/100th of a Nm?
I heve done this often with air (pcp and springers) and smallbore rifles and found an enormous improvement with all rifles.

Thanks,
Albert T (The Netherlands)

[gstarik]

Albert,
I think that if your bedding is good,you should not see much of a difference when changing the torque. Try to use dial indicator on the barrel,when changing the torque.if you see a change in the indicator (when the stock is held in a vice),than the bedding is not good enough.
A well tuned rifle will shoot differnt velocities without vertical.
When I tune,I use 1040fps and 1080fps and try to get them shoot in the same height. There is no tuning for a special lot number,because a well tuned rifle will shoot all lots to the same height. Tuning should not be made with a stationary vice,but with a vice which can recoil up,or shooting from the shoulder,or a bench. Tuning should not take more than 20min.
Guy.

[gstarik]

Hi Albert,
Can you tell us about your experiments with torque?
Are the improvements consistent?
Have you done it with aluminum stocks?
Guy.

[lilyyang]

Yes it's true that Martynon doesn't use one and has dominated the prone scene. But look at him, he hasn't changed any of his kit for years, and why would he given his scores.


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[Albert T]

Hello Guy,
Apologies for my late answer but I am suffering from the worst case of Guillien-Barre, a decease that paralises the nerve system. I am slowly recovering but it will take 5 years or more. At the moment I am shooting from a wheelchair.

I have attached a pdf document with some picturesd from my tests.
1st picture: groupdiametes with the same ammo/lot but different rimthickness; same torque with all groups.
2nd picture: groupdiameter Y-axis versus torque X-axis with different rimthickness
3rd picture: same results but now in a matrix graph
4th picture (2nd page): graph with spread of velocity starting with a clean and dry barrel using same unsorted ammo (rimthickness)
as in picture 1.
5th picture: groupdiametes with the same ammo but different torques; unsorted rimthickness.
6th & 7th picture: homemade scale in 2/100Nm on my torquewrench (Anschutz) & the homemade frontrest I use for testing.
8th picture: the differene in position of bedding bolts with change of 2/100 and 1/100NM of torque on my Walther air rifle.
9th picture: the vertical differece in hits between cartridge with powder in front or in the back of the cartridge, shot @50m.

All tests are done shot in prone from the shoulder using the home made frontrest, same rifle with standard sights and same ammo, changing only the torgue or the rimmthickness, on an open 50m range with windflags under optimum weather conditions.
I use the method of torque setting on both wooden and aluminium stocks. I found that it works on both stocks, but I find alu stocks to be much more sensitive to small torque changes.
Personally i like wooden stocks because they feel more 'soft' during the shot, but ofcourse it is only a feeling.
I have tested several torque wreches, all of the same make and type, but they all gave different readings. I have learned that you can only give accurate torque by using the same torquewrech all the time.

kind regards,
Albert T (The Netherlands)

[Fgregorio]

Hi all,
Fully agree with Guy.
From my own experience it really does work.
Not only the ballistics (vertical) of my 300m rifle improved (.308 @ 3070fps mv) but there is one more important effect that I didn't see mentioned: the increase in sight radius.
The main reason why my own scores improved a lot with a 120cm sight radius (from ring to aperture) is because the aiming becomes more accurate, the adjustments on the rear sight become finer and... the movement on the foresight (from pulse or hold) become slightly amplified.
Your brains read the increased foresight movement and you will unconciously improve your npa because your brain will refuse often to pull the trigger (glass finger) because it sees the sight picture as not acceptable.
Moreover it puts the foresight in the same focal plan as the target- no more blurry aiming mark.

Hope this helps
Fernando