I picked up a used upper today as the price was right.

Semi-Auto Smith Enterprises Bolt Carrier
S/A firing pin
Bolt unknown Manufacture no markings

Upper Reciever: Fixed handle A2. Only has a M on it so I'm guessing it's made by Martin Marietta. Wierd semi-gloss black finish. Never seen a upper with only a M on it.
It also had a A1 style forward assist on it. Lots of little dents and scratches under the finish...  It fits my LMT receiver snug but their's a little gap in between. It does not affect anything though.

The front site base is made out of steal and very nicely made. Never seen this before. really cool

The 20"  barrel is like a HBAR but the only markings are

SS
5.56

The finish on the barrel is the typical park. job so def. not stainless steel.
Also came with a A1 "Bird cage"
Seems to like 55gr so def not a 1/7

I know this is probobly a early upper someone put together but any clue who made the barrel at least???

Shoots great just needs a few part swaps and a refinish. Gives me something to do and spend more money on...

The SS 5.56 markings are OLympic arms, the SS marking mean its 416 stainless steel and its probably 1/9 twist

Is the "UP" on the FSB stamped in or raised?

Yep', that was how the Oly' barrel I had was marked.