I just got a m-16a1 upper receiver, it originally had some cracked handguards so I bought some replacement handguards for $10. I dont know who the manufacturer is but it says FNMT MP CHROME BORE

p.s. anyone else at knob creek?

I'm assuming that the marking you listed was on the barrel. It was made by FN, and is a very high quality piece. However, FNs contract (their first w/the US military) was for replacement barrels only. They never made any other major parts for the M16A1.

If you look on the right side of the upper reciever, under the rear sight, you should see some leeters molded into the piece.  Most likely, one of the letters will be a "C", which means the upper reciever was made by Colt from a forging ID'd by whatever letter(s) are along side the "C".  If the reciever doesn't have a C, but some other ID letter(s), then it too was probably a replacment piece.

Quoted: p.s. anyone else at knob creek?

.........................buying lowers at the local fun show tonight