Question on Colt A2 20" upper with M4 feed ramps

[masakari]

That upper has been modified by an aftermarket party. It is too old to be relevant to any other discussion in this thread.

Colt only did non-anodized feedramps during 1999-2000ish on some 6520s.

Can you explain further?
I should note that the feed ramps appear to be anodized, and I think what you're seeing is a reflection.

[scottryan]

Can you explain further?
I should note that the feed ramps appear to be anodized, and I think what you're seeing is a reflection.

A 20" rifle of that vintage should not have any extended feedramps.

The only 20" rifles that ever had extended feedramps are the current AR-15A4 and some neutered postban 6601/6700 HBARs.

If the feedramps are anodized, then that upper was removed from a fixed handled carbine and was mated with your barrel. That receiver was from a preban gray 6520 carbine made around 1989-1991 with a large front pivot hole.