Has anyone ever had or heard of a problem with a 7.62x39 Arsenal AK-74 muzzle brake (SKU: AK-140B) not being threaded deep enough?

I picked one up to swap onto my Arsenal SLR-107FR and it seems like the threads inside the brake are about a 1/4" too short and it won't screw on enough to even engage the retainer.

Yup, this is a short collar brake, you need a long collar to fit…short on the left, long on the right.

my 107FR came with one on it, what was on the muzzle of yours?

oof. I assumed with Bulgy threads and 7.62 it would work. How do you know the difference when ordering? Just the profile at the threaded end?


Mine came with the 4 port birdcage flash suppressor.

K-var sent me a return authorization, no comment on what the issue is/could be, so I returned it. For reference, some pics below.

The new AK-104S mount on the right (with the chrome lining) next to the mount off my SLR-106FR (with the green copper fouling ). Note the depth of threads.
Attached File


Here was the new mount on my SLR-107FR, didn't quite make it on.
Attached File


Here's the mount form my SLR-106FR on the 107. Interestingly, it has the same external profile as the problem mount, but screwed on all the way.
Attached File

That’s odd, just replied to your IM…makes me now think it may be out of spec?