Which Upper is the least Finnickey?

[azreloader]

I am getting a new Lower from ASA on Friday and will be looking to buy an Upper that will digest most anything. (ASA uppers are known for being ammo sensitive)

Which Upper, in the cumulative experience contained herein, is the least finnickey about what it eats? I am looking for an A2 or A3 20" National Match configuration. :letssee:

[shamayim]

Colt, Bushmaster, Rock River. Those are the ones I have personal experience with, and they all work just fine.

[azreloader]

OK, since 100% of the people responding included Rock River Arms as one of the best choices, and their direct ordering prices were the most attractive, that's what I went with. i ordered a 20" A4 Complete Upper.

When I combine it with my ASA Lower, I will have an "ASARRA"

When I have all the parts and can take it out and shoot it, I post a Range report. (reading the DEA torture test results helped sway the decision)