free floating the air cylinder.

[kevingambrell]

I read an interesting article on one of the bench rest forums about free floating the air cylinder on the 400 series rifles.
Its an easy job using 15 thou shims in front of the stock screw and behind the screw.
Had a try at it yesterday and was more than happy with the results. The point of impact shifted 1\2 inch down and the groups tightened up by a cgood percentage.
Well worth more looking at!

[Kev Todd]

Couldn't agree more, why don't aa do it as standard......?

[poguemahone]

i free floated mine in 2010 when accuracy suddenly went out of the window. i usually get into arguements if i advise anyone suffering accuracy problems, to try the £5 note test, then float the cylinder, so i tend to offer the advice via pm. usually get a pm back saying its sorted the problem
some stocks dont touch the cylinder so dont really need the cylinder floated, but i would float it anyway.
wood can and does warp/change shape very slightly due to drying out, getting wet, or a combination of both, and the slightest touch on the cylinder can affect poi.
the thickness of shim required to float the cylinder needs to be thick enough to pass the £5 note test at the very least.
to those who dont agree that floating the cylinder is beneficial, count yourselves lucky that you're not one of the 10-15% who NEED to
float your cylinder, thats my advice

[devonhunter]

Kevin could you provide a link please interested in how this works

[kevingambrell]

Kevin could you provide a link please interested in how this works

I will trawl back through the history on the PC and find the link.

[devonhunter]

Thanks

[poguemahone]

worth noting that cylinders can change at different pressures and touch the stock causing problems. did a gun for someone a while back that passed the £5 note test at 170bar and 120bar, but trapped it at around 140bar. this explained why the gun had a poi shift in the middle of the sweet spot. floated the cylinder and accuracy was spot on all the way from 170 -120

[devonhunter]

Don't get it

[Blackbaronfish]

When your action is tight against the stock it doesn't allow the barrel to naturally sit and changes the harmonics. At different pressures the cylinder changes shape and pushes the figure of eight against the barrel thus changing poi.
If you free float the barrel this will stop all the above. You could also bed the lot in with Devcon

BBF

[Raj]

Good old film negative works well as a shim. Wont mark the cylinder as it is not metal and wont get damp and cause rust like paper would.