Unmarked AR barrel?

[WestKentucky]

I bought a used barrel sight unseen to use as a mock-up for a project. I expected pure trash and ended up with a barrel that seems serviceable. It’s a bit ugly from some sort of surface rust and something that looks like bronze paint transfer. The barrel is 16” from face of threads to the flange on the extension and is totally unmarked. It had a pinned on sight tower, and the previous owner said it came off of a bushmaster gun. Is there any way to halfway figure out what it is? I’m still going to use it but I may be more gentle with it in my mock-up and I may actually use the barrel. A set of military type irons would be neat on the gun I’m building so I may run with the pin-on sight.

 

[cfullgraf]

You can make a cast of the chamber and then measure it to determine what it is chambered for. Slug the bore as well.

 

[WestKentucky]

You can make a cast of the chamber and then measure it to determine what it is chambered for. Slug the bore as well.

It’s pretty clear that it’s a 5.56 barrel. A 223 rem drops right in nice and snug. The barrel is odd. Kinda hbar cut but threaded and 16” I’m hoping to see if it shoots. I’m at least a year out on that though I would guess.

 

[gotboostvr]

It’s pretty clear that it’s a 5.56 barrel. A 223 rem drops right in nice and snug. The barrel is odd. Kinda hbar cut but threaded and 16” I’m hoping to see if it shoots. I’m at least a year out on that though I would guess.

That wasn't a terribly unheard of barrel type (16" Hbar). It does seem much less common now though. Most likely a 1:9 twist.

 

[bfoosh006]

Good point on the twist rate.

Bushmaster used quite a few 1n9 twist barrels... anyway you look at it, knowing the twist rate should narrow down your choices.

What gas system length ?