I have completed my M4.  It is highly no-ban and high-speed/low-drag modified, but the base rifle was a post-ban Colt MT6400c.

Anyway...

I am now considering building/buying a 20" rifle.

A few things to satisfy my pet-peeves:

1) It has to be all Colt.
2) It has to be no-ban compliant with all evil features in tact.
3) The barrel has to be 20" Government profile 1 in 7 with full chrome lined barrel and chamber.

I can't decide on A2 or A4 so I am considering both.

I am thinking about buying a Colt MT6601 (Match Target HBAR).
Remove and sell the barrel.
Buy one Colt M16A4 upper receiver assembly.
Buy two AR6551 20" Colt chrome lined Gov't 1 in 7 barrel and front sight assemblies.
Put one of these barrels on the MT6601 upper receiver and the other barrel on the M16A4 upper receiver.  Put a BUIS and an Optic on the M16A4 upper.
Interchange uppers as desired.

Is this reasonable?

I’m doing the same thing.



What you see in the pic are both Bushmaster rifles, both an M4 and an A2; the Colts are next.

Your plan doesn’t sound reasonable, but it’s probably going to take something like that to get it done. I’ve thought about having the upper built by SAW, but that’s going to be a pretty penny. You might also look around for some good used parts if that would work for you.

No.

I would not do it...