Just purchased a new flat top. The finish is dark.  Blackish/gray.  The outside seems to have recieved a good coating but the rear is light gray, silverish where the anodizing is very thin. The interior surfaces reflect the same thin anodizing.  I've owned 6 AR's, all Colts and have never noticed the lack of finish.  

Will my upper wear differently with the lack of interior finish?  Should I send it back?

I've heard of uppers having a dry film coating/lube.  Do all uppers have this?

Thanks

If it's a Bushmaster upper, the light gray is almost certainly a dry lube coating, which has been applied OVER the anodising. If so, woory not[:D]. It's to assist w/breakin.

If you hadn't specified it was a flat top, I would have asked if it was a milsurp M16 or A1 upper, since I've seen many w/ that coating also. Now the Colt experts on this board will tell you that Colt never put that coating on their pieces.  Who am I to argue with them[:D]? All I know is that I've got two mil surp Colt uppers with exactly that color and coating.

Its a flat top that was purchased from an advertiser on the board who says it is by the same company that supplies BM and RR.  It has a "keyhole" logo on the right side.

What is strange is that my new BM barrel will not slide into the opening.  It goes in about an 1/8 of an inch and gets stuck.  In a Colt upper, the BM barrel slides in perfect and snug.