Help identifying AR upper

[JMHL]

Go this upper in a trade, I was told that it's a Bushmaster upper but i cannot find anything to confirm it. Only mark i can find, is a square on the receiver but i think that is a forge mark. It has a free floated carbon fiber handguard, 16" fluted barrel with a quick detach muzzle brake.Here are a few pics. Thanks in advance.

[hossb7]

quick detatch muzzle brake?

[TKM]

http://www.baforging.com/m-16-and-ar-15-components.html

http://www.calguns.net/calgunforum/showthread.php?t=356555

[pinoy916]

Unless its billet the recvr is a recvr, square, keyhole..etc. I have seen Noveske uppers with square and keyhole marked, recvr is standard. I have seen Bushmaster with keyhole and square recvrs.
The barrel looks Bushmaster.

[bohoki]

looks like the "carbon 15 barrel" bushmaster uses various sources for upper receiver forgings

[Akers]

Square is Brass Aluminum Forging Enterprises. That I know, still looking through my stuff on foreend and barrel.

[Akers]

As bohoki said, I really think it's bushmaster.

[Heavy_Grinder]

Don't know if this helps but the last upper receiver I bought directly from Bushmaster had a "Y" mark on the end of the receiver. It also had a semi-purple hue to it.

I've bought many upper receivers from all sorts of manufacturers and this bushmaster receiver was the only one that had that color to it.

[JMHL]

Seems to really be a Bushmaster then, thanks for all the input.