Need help identifying this old c.a.r.15 upper?

[Burning Love]

Pop the handguards off and check the barrel

 

[Jamescg]

Pop the handguards off and check the barrel

I DID, NOTHING NO MARKS AT ALL, THE FRONT SIGHT BASE HAS A GAS WHOLE OUT THE FRONT, I SAY THAT BUT I DONT THINK GAS COME OUT IT JUST LOOKS LIKE IT WOULD A ROUND WHOLE WITH WHAT LOOKS LIKE A SET SCREW MAYBE?

 

[rockyfatcat]

As a USAF military working dog handler, I carried the M-16/GAU 5A. Your upper looks pretty similar. $250?

 

[Triptones]

Love that setup I want it. Nice score!

 

[Cal B]

Mine I believe is Bushmaster

 

[IMDB]

There was a company back in the late 70s early 80s called Sarge or Old Sarge that was selling ar parts. It's probably an Olympics arms upper.

 

[Jamescg]

Here is a picture of the fsb and the chamber and bolt, maybe colt because of the smooth fsb and gas tube plug, the bolt looks like a colt a1 maybe it has been replace? Barrel look non-chrome lined? I can’t figure it out it’s making my head hurt!