I'd like to second what Frisket said about getting the plain ole AR style rifle... I've shot several of the piston guns, and all of them were heavier and had more recoil than my traditional gas tube guns...if you aren't shooting a full auto AR it is really a non issue... if you shoot a lot of Wolff ammo, just clean the bolt every time you come home, and keep the 3 piece ring set and not try to use one of the one piece rings...

the heart of an AR is the trigger... would suggest you look at the Rock River rifles that come with a good National Match trigger as original equipment.... depending on what you are using it for ... would suggest a full float front end (without all the rails, possibly a lower rail only for vertical grip) and if you go with a carbine .. a 16 inch barrel with the intermediate gas system...

my game gun is a RR 16 inch as suggested with 4x32 ACOG, modified Miculek muzzle brake, with a VietNam era A1 stock... it particularly likes S&B 55grain ammo, and will hold 5inches at 400y... I can't see any better than that...