Where to buy parts:
http://www.model1sales.com/: Sells Complete Pistol kits as well as pistol buffer assemblies
http://www.dpmsinc.com/10Expand.asp?...ode=BA-A2AS-07: DPMS Kitty Kat upper has a solid reputation
http://www.olyarms.com/?page=m1_oa_models: Olympic Arms OA-93 upper and
manual on how these work