[zaitsev]

Fellows, I recently acquired an upper in a trade. Is there a tell-tale way to identify manufacturer. The barrel has an indentation as if for mounting something just forward of the bayonet lug. The bolt has a "SE" in a little square if that means anything. It fits on my eagle/armalite m15a2 lower real nice. As you can tell I dont know much about these things..
Thanks

 

[Flak 2]

zatsev. The SE on the bolt stands for Smith Enterprises. There might be markings on your barrel also between the front sight and muzzle. As for an indentation in front of the sight base thats a new one to me. There also might be some codes on your upper reciever.