Quote Originally Posted by Spartan040 View Post
Looking to build an AR for myself, can't decide if I want direct impingement or piston. Piston runs cleaner and cooler and (I've heard) can generally take more abuse and less lube before it begins to fail, and if there are minimal reductions in accuracy and a tiny bit more felt recoil, I don't really mind. But, I've heard there are certain mechanical issues associated with piston AR's. I wanted to know what they are, and if there's anything that can be done to fix them in a custom build. I've also heard availability and interchangeability of parts is another factor. Are the advantages of the GP system worth the trade-offs?

You will not be building a piston AR-15.

Every "bolt on" piston kit is garbage.

If you want a piston, then you must by from Colt, HK, LWRC, or LMT.