All AR15 piston systems are add ons, most are copies of the Armalite AR180 system with a little tweak here or there. They add some weight to the rifle. If I was going to choose one I would choose one with a 1 piece carrier and a pinned gas block or I did choose a SCAR over every high priced AR with a add on piston system. I think I would even choose my $700 Armalite AR180 over most of the piston rifles on the market.
Last edited by Constructor; 02-14-2011 at 10:31..