Just picked up a used USR rifle ... have a few questions about legalities can i add a take down button for the barrel? it seems like it might fit ... but 1 is it legal and 2 is it easy to do ? can i cut the barrel down and add a pinned down muzzle brake ? the law says no flash hiders , so would a muzzle brake be ok ? and if so , can i use one of those AAc's that would allow a suppressor to be attached? research seems to be not so much in favor of suppressing this rifle due to piston port noise .... anyone did it and can comment ? the 20/20 trigger sear seems to be the best part to improve the trigger... any recommendation ? thanks in advance!