What is this groove for?

[smokedog]

At the risk of looking like a total idiot, here goes.
20" NM barrel.
What was on here or whats it for?

 

[outrider58]

No clue. I'm just curious, what did the barrel come off of?

 

[Vic]

Muzzle brake?

 

[ken792]

AWB era or ban state for a set screw muzzle device?

 

[smokedog]

No clue. I'm just curious, what did the barrel come off of?

It's on a 20" upper I picked up 2 weeks ago.
Just .556 NM on the barrel no other markings anywhere.

 

[outrider58]

It's on a 20" upper I picked up 2 weeks ago.
Just .556 NM on the barrel no other markings anywhere.

Thanks.

 

[Bountied]

Front hooded peep sight?

 

[BFMIN]

Attaching a muzzle device of some kind. Brake, flash-hider, or similar. you can see the scarring from the 3 attaching screws.

 

[TheOriginalMexicanBob]

Some ARs during the assault weapon ban used muzzle brakes rather than flash suppressors and these were pinned on rather than threaded.

 

[smokedog]

I did some googlefu and didn't come up with anything to pin on that.
It's a mystery, maybe I'll just thread it.

 

[TheOriginalMexicanBob]

Threading can be done...I had an AR with a pinned muzzle brake threaded and a flash suppressor installed.

 

[outrider58]

I found this...

Compensator Nine Holes Set Screws

Post ban style compensator held on by four set screws. Inside hole is .702 Made from aluminum Over all length is 2.250 Outer diameter is 1.0...

innovativeindustriesllc.com

 

[smokedog]

I found this...

Compensator Nine Holes Set Screws

Post ban style compensator held on by four set screws. Inside hole is .702 Made from aluminum Over all length is 2.250 Outer diameter is 1.0...

innovativeindustriesllc.com

May order one.
Thanks

 

[BFMIN]

I did some googlefu and didn't come up with anything to pin on that.
It's a mystery, maybe I'll just thread it.

They weren't pinned, & didn't need to be, because the muzzle wasn't "threaded to accept a Muzzle device". Instead they had 3 grub screws at 120° angles to clamp & align. You can see the scars from them. It was a legal way round the "neutering of assault weapon features"! They were really popular for a while. There were dozens of versions of them.

 

[outrider58]

They weren't pinned, & didn't need to be, because the muzzle wasn't "threaded to accept a Muzzle device". Instead they had 3 grub screws at 120° angles to clamp & align. You can see the scars from them. It was a legal way round the "neutering of assault weapon features"! They were really popular for a while. There were dozens of versions of them.

(see post #12)

 

[P-12 Norm]

At the risk of looking like a total idiot, here goes.
20" NM barrel.
What was on here or whats it for?

Attaching that thing that goes up?

 

[smokedog]

Attaching that thing that goes up?

SSSSHHHHHH don't tell no body

 

[P-12 Norm]

SSSSHHHHHH don't tell no body

Especially Diane Foreskinstein.

 

[Kman]

It's for shaking.

 

[BFMIN]

(see post #12)

Yes, exactly!