I went to my local gun store today, and inquired about getting a ar-15 m4 type carbine. I was told by the gun smith that I could have a rifle built for around 750$ + 50$ to put together. Instead of buying a Colt 6920, which I have been eyeballing for some time now. They would use a DSarms Lower receiver, spider tactical cold hammer forged 14.5 inch barrel with a flash hider that would put the rifle in the nfa specs. I can upgrade any trigger parts I like, the furniture would most likely be magpul. I am not sure which upper receiver they would use. It would also have a m16 bolt. The feed ramp was smooth as well going into the chamber. I plan on using a ACOG on this rifle.I used M4's in the Army for the last ten years, just got out of the service this month. I really want a M4 type rifle, as I have a lot of goodies already for it. I would love to hear your opinions on this set up and /or suggestions. I also have a Springfield M1A, my long distance shooter, and a Norinco Mak 91 for fun. Thanks in advance.