I have a Colt upper with the Alcoa Forge AF marking "C AF" stamped on the side.  On the front, just above the gas-tube hole, there is an "M4" stamped.  The barrel is heavy under the handguards, from the FSB back, with the "M203" cut-out a on the heavy contour.

When I got it it had tan, OD and brown paint on it, and it looked pretty well worn (the paint).  I removed the paint, and underneath the finish was in probably about 95% condition, the shell-deflector had a bit of wear, and a couple knicks that look like they came from handling, and a couple marks on the edges of the top rail that looked like it was from mounting an optic.  From the paint pattern on the upper it looks like it was painted with a QRP-mount on it, but I can't be sure of that.

Bore is bright and shiny, no pitting, and it has M4 feed-ramps on the barrel extension which don't look very worn.  Came with what looks like a standard A2 bolt/carrier in pretty good condition.  FSB is marked "M5 I 1."

I got the upper from someone claiming it was from the military.  It has a C MP 5.56 NATO 1/7 14.5" barrel, had no flash-hider when I got it, but had a crush-washer on it.

So, what my question is, is there any way to tell if this was used by the military like the guy said?  Was this combination of parts used by the military? Would the military DRMO uppers that have good bores and no structural damage with pretty much new-looking parts? Or is it more likely a bunch of civie parts slapped together?

Thanks for any help you can offer.

No one has any ideas as to whether this upper could have been used by the military?