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Power limits

Posted: Fri Jan 05, 2007 1:12 pm
by gunslung
I use an Air Arms S400C converted for 10m target shooting, I've got anschutz sights and a spirit level installed on it, and I can get tight one hole groupings with it at the 10m range and its accurate to about 60, though I havent tried it with the ring sights at this distance.

The only problem is that its tuned to just below the UK power limit of 12ft/lb and is not adjustable without special tools.
Is this power set too high for serious competitions? if so, is there anyone in the uk I can send/take it too for this kind of power tuning?

Posted: Fri Jan 05, 2007 5:52 pm
by Jim E
Research done to develop the wadcutter, 10M pellet, determined ideal velocities in the 570 to 575 fps range. Ideal meaning the most consistent pellet stability. Higher velocities, such as those used for Field Target, are not advantageous for 10 meter air rifle.

Power levels for 10m

Posted: Sat Jan 06, 2007 7:24 am
by peepsight
Jim is quite right in what he says concerning the power for 10m match air rifles.

All the match air rifle manufacturers work to a formula in conjunction with the pellet producers for the most consistant velocity and tightest grouping
over a 10m distance.
The formula is, barrel length/number of twists in the rifling over that length, barrel time/velocity of pellet, pellet weight and size, choke size and consistancy of compression behind pellet for consistant velocity.
Most of the top rifles are consistant to within 6-8 FPS. Anything over 10 fps and i would be worried.
When all these criteria are met and are running consistantly you now have a hightly accurate rifle.
Too high a velocity is not always an advantage in 10m shooting plus some range officers may not be happy because of the possible damage to target holders etc.
I suggest you contact Airarms and ask their advice to see if this can be achieved on the model you have. I have my doubts.
Spirit levels are not allowed under ISSF rules for 10m air rifle.

Peepsight

What? !!!

Posted: Sat Jan 06, 2007 11:47 am
by guess123
What does Jim E. means by 570 to 575 fps is ideal? What is he? a 10-meter air gun designer for FWB or Walther? or maybe Jim have an engineering degree?

I shot two FWB P700 thru the chrony and registered an average of 595 fps.

Also what does "...Most of the top rifles are consistant to within 6-8 FPS."
That two P700 and a P70 I shot have consistancy over 12 fps spread (10-shot string) between high and low, yet all shot a one hole group.

Posted: Sun Jan 07, 2007 10:18 am
by gunslung
hmm... I guess my Air Arms is good enough for practice...
its pretty awesome for a sporter realy...

not enough time to think about air rifle competitions now though, I've got enough to deal with in .22lr and fullbore

Posted: Mon Jan 08, 2007 2:07 am
by cdf
In addition to what has already been mentioned , noise would prolly be an issue with other competitors and range officers . Higher velocities can produce more leading - not too good for accuracy . Wadcutter pellets dont like extremley high velocity , they are engineered for a lower velocity range . 10 Meter match rifles are a carefully engineered product , wit a lot of complex trade offs .

Chris