[Darklen]

I used to use silicone chaulking when installing scope mounts on high powered rifles (real steel). It seem to absorb the shock well and the screws didn't back out. Never tried it with a piston head (I use locktite all the time at work, so I have everything I need in my home shop), but I can't see it hurting. Just wait a full 24 hours for it to cure properly and make sure there's no oils, silicone or otherwise on the curing surfaces. Hell, you could even try a wrap of teflon tape (plumbers tape), it'd probably work fine.