Muzzle brake issue - seized up

[phylodog]

Need some advice here. I just got in a Rainier Arms match barrel today and a brand new Surefire muzzle brake yesterday. After installing the barrel I began the process of getting the brake timed properly. It was a tight fit so I confirmed that both the brake and barrel were 1/2 x 28, which they were. I put some oil on the threads and slowly worked the brake on, stopping when things got tight and backing off a turn then tightening further. It was tight but nothing I wouldn't attribute to tolerances. I removed the brake which came off easier than it went on and looked for burrs or anything on the threads, all looked clear. I then went to reinstall the brake to determine which shims I would need to add to time it properly and it seized up on me 1/8" shy of full seated. I've added penetrating oil and at this point I know the threads are wet but it won't move more than about a half turn in either direction.

I've got it in the freezer now. The only thing I know to try is to get it good and cold then hit the brake with a MAP torch to heat it up quickly to see if that will allow it to come off. Any other suggestions?

 

[churchmouse]

It sounds like one of the threads has peeled and rolled over. I am pretty sure the will be damage when you get it off. You are on the right track with the cold/hot thing but from your description something is in the threads.
Hope I am wrong
I have a 1/2X28 tap but not a die. I would have wired the barrel threads and ran the tap in the muzzle break.
If you need the tap let me know.

 

[phylodog]

Thanks CM. At this point I'm just wondering if I'm screwed out of more than $300. Getting either Surefire or Rainier to do anything is going to be difficult, if not impossible. Pretty easy for each of them to blame the other and I have no way of proving which caused the issue.

 

[churchmouse]

Depending on what and how much gets damaged a tap and die might square you away.
The rotating to a stop is what scares me. You will have to get past that point. If it is a thread rolled up in there it will do some damage.

 

[phylodog]

Carnage

 

[SEIndSAM]

Dang!!!! That doesn't look good.

 

[phylodog]

Looks like $350 sitting in the bottom of a port o john from where I'm sitting.

 

[churchmouse]

Looks like $350 sitting in the bottom of a port o john from where I'm sitting.

That can be saved Phylo. May not be pristine new but it will have zero effect on accuracy.
That can be saved.

 

[Squirt239]

Bring it by. I'll get you fixed up. Couple minutes on the lathe and youll be good to go.

 

[churchmouse]

Bring it by. I'll get you fixed up. Couple minutes on the lathe and youll be good to go.

Yup^^^^^^^^^^^^^^^^^^^^^

 

[phylodog]

I appreciate it, may take you up on that offer. I've got an email in to Rainier to see if they've had this happen before (bad threading). Hoping they'll replace it. The biggest problem I have is that I don't have much wiggle room to cut the barrel back and rethread. The suppressor comes to within about 1/8" of the rail as it sits now.

 

[phylodog]

Took some measurements but I don't know if these are indicative of what they issue may have been.

Unaffected OD of the barrel threads

Unaffected ID of the brake

 

[30calmachinegunner]

I'm going to assume( bad juju) that since your using a sure fire break that it is for a quick attach suppressor. If so once you put the break on is won't be coming back off, if that's the case the threads in both parts can be cleaned up ( I have a tap and die) the break installed and only you will know. There's enough threads left to be sufficient.

 

[phylodog]

You would be correct 30CMG. I considered having it pinned and welded in the event I decide to purchase another lower at some point and make it a complete rifle. My concern at this point is if I caused any damage to the barrel applying the torque required to get this thing off. I'm not expecting .25MOA but I need it to be minute of coyote out to 300.

 

[churchmouse]

I'm going to assume( bad juju) that since your using a sure fire break that it is for a quick attach suppressor. If so once you put the break on is won't be coming back off, if that's the case the threads in both parts can be cleaned up ( I have a tap and die) the break installed and only you will know. There's enough threads left to be sufficient.

This is how I would fix this. There is ample thread left. Clean up the trashed area. Tap and die. Bingo.

 

[30calmachinegunner]

We can always pop the barrel in the lathe and check it for runout but I doubt you did any damage to it other then the threads

 

[1911ly]

I'd think that brake had a bur in the threads. As you backed it out it it peeled metal off the barrel. That sucks. Tap that break and I'd take 30cal up on his offer of the use of a lathe on that barrel. I don't thing a die will easily start on that.

 

[ljk]

just make sure you measure the barrel with a dowel rod to find out the actual barrel length from the bolt face to the muzzle before doing anything to it.

 

[phylodog]

It's on a SBR lower so no worries about legality, it's 14.5" now. My only concern on length is whether I can clear the rail with my suppressor. I've measured the OD of the undamaged threads on the barrel with a set of dial calipers and two different micrometers and I'm getting between .5025"-.503" which is larger than they should be. I'm hoping Rainier will replace the barrel for me.

 

[churchmouse]

I'd think that brake had a bur in the threads. As you backed it out it it peeled metal off the barrel. That sucks. Tap that break and I'd take 30cal up on his offer of the use of a lathe on that barrel. I don't thing a die will easily start on that.

Cut back the damaged area and use a file to get the thread ramp back and run a die down it. Clean it right up. Repaired worse.