AR Barrel (DPMS) thread problem

[spencerhut]

So I was helping a buddy build his first (civilian) AR last night and when we took the muzzle brake off to install a low profile gas block it seemed harder than normal to get the brake off. I thought it was Locktite, but it was not. Look carefully at the image and you can see an almost perfect round deformation in the threads, like the barrel was drilled and filled with a dissimilar metal?


I was going to get a 1/2-28 die and clean it up, but thought I should mention it here first to make sure I'm not missing something.

BTW - I have the exact same part number barrel on my wife's AR and we did not have this issue with it.

[jon7400]

It was likely a "Post Ban" barrel and had a compensator meant to be permanently affixed. That looks like a light "pin and weld" to me.

[spencerhut]

I should have mentioned this, the inside of the compensator is normal, no thread alteration and no signs of any means to secure it other than the standard barrel nut.

[CHS]

14.5" barrel?

Re-purposed barrel?

[spencerhut]

It's an advertised 16" barrel. I'll measure it when i get home.

http://www.midwayusa.com/viewProduct/?productnumber=896061

[joelukehart]

Call up DPMS and ask what their take on it is. It looks like you have plenty of good thread behind the blem so a die should clean it up well enough for another muzzle device. If you want to get really fancy chuck it up in a lathe, part it off where the bad threads are, and recrown. (as long is it over 16 inches). You should also check and see if the muzzle is deformed.

[spencerhut]

Call up DPMS and ask what their take on it is. It looks like you have plenty of good thread behind the blem so a die should clean it up well enough for another muzzle device. If you want to get really fancy chuck it up in a lathe, part it off where the bad threads are, and recrown. (as long is it over 16 inches). You should also check and see if the muzzle is deformed.

It's right at 16". The brake is fine, the nut is is fine, just this one spot on the barrel is jacked up. I'm going to clean the threads and call it good.

I was just wondering if this was something common these days since I've got the exact same upper on my wife's AR and did not have this problem. I'm pretty sure her muzzle brake was Locktited so I am leaning towards DPMS using a dissimilar metal plug in place of Locktite.