TargetTalk

The latest ISSF News brings a very interesting interview with Niccolo Campriani. The main subject: the project to develop a recoiling locking clamp for ammo tests. Nice idea, but pretty old. Such clamps are known as Kudelin's vise. What I do not like in the article is the fact that nobody even mention that. I realize that the ISSF News is not a scientific journal, but...

http://www.issf-sports.org/media/magazi ... df/615.pdf

Doesn't the Kudelin rig just allow the rifle to move back in a straight line? That's not quite the same effect as simulating the resistance of the human shoulder. However he's not the first to attempt it. Back in the 1950s Eley borrowed a test rig design from Winchester, which supported the rifle loosely in a cradle, with the butt against a firm stop and a weight was hung from the fore-end to simulate the pull of a sling (standing was not on their agenda at the time).

Yes, indeed. However, the statement "This process, however, has always been conducted with a rigid lock" is misleading. Anyway, the project can be fruitful as done in colaboration with Ferrari engineers :-) Case to follow.

There are so many variables testing ammo for 3-P I'm not sure how much you can take from any test vise.
Sure, you can find some ammo that tests well in the rifle as is clamped, but for the "magic pill" for all 3 positions I can postulate you can only get close .... and it may be "good enough".

Variables such as sling point attachment, sling pressure, pressure and angle of that pressure in the buttplate(s), cheekpiece(s) pressure & angle, grip tightness, sights positioning ... (and many more) ... all effect the recoil/damping properties of the rifle.
(I'll admit I'm a nerdy engineer who works on vibration/modal reduction projects so I may be over complicating it)
If you are only testing for prone ... maybe a touch easier

I'll say that I prefer not to test in a factory jug w/o the stock, but clamped in the stock, bedding bolts tightened & sights on, and find a lot that shoots the best for that situation. I really don't expect it to shoot the same in all 3 positions.

Don't know if anyone has taken it to the extreme (???) of different ammo in different positions, but it would not shock me any.
Is the (small) variability in the ammo from a single lot even worth that?

None of this (post) is really useful info ... just a long winded question.....

It was not my goal to start a new topic on "ammo tests", as there are many already running on TT. Just to notice the article in the ISSF News. As a physicist I like such projects, and even 8 years ago I made my own "clamps" inspired by Mr. Kudelin's idea. First, it gave better grouping than rigid clamps, but qualitatively changed nothing - better ammo from rigid clamps was better from the slider too. So...
Let's observe how Niccolo Campriani deals with the problem. As he is an engineer, after Rio 2016 maybe some interesting devices will be presented to the public. ;-)
My modest clamps are below :-)

Grzegorz wrote:.... - better ammo from rigid clamps was better from the slider too.

All the testing I've done .... and to those I've talked to, the above statement just about sums it up.

It WILL be interesting though if a different answer comes out of Italy!