Well I know what I want so far. Please keep in mind this is my first build and I'm not holding back very much when it comes to how much I'm putting into it. But there is a limit. I'm going with an Ops-4 ambi upper receiver, spector length ar stoner ss fluted barrel with a 1 and 8'' twist rate, tromix shark muzzle brake/flash hider, samson evo 9 ex free float, dimondhead front sight and troy rear DOA sight, AX556 ambi stripped lower, timney 3lb skeleton trigger or wilson combat two-stage trigger, stark qd pistol grip, full CAA SRSS, Brownells EZ takedown pins, and probably get a yhm Titanium Q.D. Phantom 5.56 unless someone knows of a better one within that price range. Then an anti-tilt buffer...not sure which one to go with though...any suggestions? Obviously there are things missing. Like for instance which buffer tube should I use with my CAA SRSS? But most importantly I cant figure out how, where, which or if I can get a Short stroke gas piston system to funtion with my free float setup. please keep in mind I'm new to this and am doing my best. I'ts taken me a long to time to finally decide on this exact build which I love to death and can't wait to assemble. What else am I missing besides optics? Thanks for your time guys I really appreciate it.