I'm not exactly stupid, not exactly. But, I have had this CAR15 kit sitting around for a while, I'm starting to assemble it and I noticed yesterday that the barrel has what I think are the M4 feed ramps, the two little rounded reliefs cut in the bottom side of the chamber end of the barrel. Are those the M4 feed ramps? and if so, is this odd for a 16" Hbar? This barrel also has no markings, zip. I hear that these M4 feed ramps are a Colt proprietary design.  ?????
            Thanks for any help, R.

M$ feed ramps are cut into the aluminum of the upper receiver.  They act as a ramp to the ramps you speak of that are cut into the bottum locking lugs.

slt223, thank you, I knew I was missing something, there is so much to learn.

Just a little elaboration.

The M4 (and now M16A4's) have deeper feed cuts in the barrel (all barrels have feed cuts) that extend into the upper receiver - to which those receivers have cuts in them - this is intended to enhance full-auto reliability.

Right on guys, I looked at my M4 barrel and saw the deeper cuts and checked my M4 upper and saw the corresponding cuts in the upper receiver. On my upper it has M4 above the clover leaf, same dif?          And nice photography!
Thank you, I'm feeling smarter already. R.
I owes ya