The site where I play runs what they terms as a hybrid day with punters and own gunners. Everything counts, heads, gun the lot.
Mainly woodsball but with sup-air bunkers thrown in for more fun...
we have to run our markers in semi mode only, 290fps max and lock 'em down to under 15bps to keep things sociable.
Also use a 5-7 min 'invincibility' whereby if you get shot you return to your start point, clean up and go back in, keeps everyone happy and gets the paint used up....