A lot of help needed with AR barrel

[technetium-99m]

Ok guys, big problem here.

I had my LR-308 barrel turned down and threaded for a Rolling Thunder comp. I get the barrel home, Cerakote it and test fit everything together, comp goes on no problemo, thread on the barrel nut and all looks well for tightening the nut down so I torque it. I start to take the comp off to put some red loctite on and it gets about halfway off before it stops cold, no loosening or tightening. I think "huh strange." I put a large punch through the comp to get some leverage and I hear BAM!

The pin on the extension sheared and the barrel came loose from the extension. I said "oh my," or something to that effect only more colorful.

Long story short the comp is still frozen on the muzzle, the extension is no longer tight to the barrel, and the pin that locates the barrel in the upper is broken.

Where do I send this thing to to fix it? Putting on extensions etc. is out of my pay grade.

Edited May 6, 2011 by technetium-99m

[whistlepig]

Short of sending it to a professional shop I have one on the cheap suggestion. If you know any law enforcement in your are, they likely have at least one firearms guy who will ba an AR15 armorer. While they alomst exclusivly use the .223, an armorer can look at it and if the right size tools are avail, the extension issue is no biggie. If you want a pro builder who is very experienced in .308 AR's, call Steve Adelmann at Rifleman Consulting in NC.

www.riflemanconsulting.com

[esskay]

Yikes!

I suspect that many folks (like me) just use upper vise blocks when working on their uppers.

Is the OP's situation an example of why we should be using barrel clamp vises instead? Or just an unfortunate and rare fluke?

[technetium-99m]

Oh the upper was in a vice block alright. The barrel nut torqued down just fine. The problem came when I used too much muscle to get the comp un frozen. I think I accidentally got some cerakote up inside the comp since the barrel threads were masked off.

I found that new locator pins can be had, but I still need help getting the extension back on and the freaking comp is still freaking frozen. (verbage changed for public display)

Let this be a lesson to you guys, do not get cerakote up inside the threads of the comp, it will magically freeze when you take it off and then you are in a world of hurt.

Edited May 6, 2011 by technetium-99m

[esskay]

Bummer...

What I meant though was using a barrel clamp type of vise, which would theoretically avoid putting pressure on the barrel extension pin when you were muscling the comp:

As opposed to the typical upper vise block (which is what I use too):

[technetium-99m]

I gotcha, and I think you're spot on!

Yes the vice blocks would have been a much better tool for the job! The correct tool even!

I just figured since the comp went on easy it should come off easy. Live and learn, pay someone to fix it if you break it.

Now to find someone to fix it, I'm going to talk to the gentleman who cut it down, but I'm not thinking he can reinstall the extension. And on that note, how the hell did the extension come off with hand pressure?

Edited May 6, 2011 by technetium-99m

[kurtm]

J.T call up Benny and have him help you out, drop my name wantonly and I will talk to you this Saturday! Bummer man! Kurtm

[Mark Gale]

Ok guys, big problem here.

I had my LR-308 barrel turned down and threaded for a Rolling Thunder comp. I get the barrel home, Cerakote it and test fit everything together, comp goes on no problemo, thread on the barrel nut and all looks well for tightening the nut down so I torque it. I start to take the comp off to put some red loctite on and it gets about halfway off before it stops cold, no loosening or tightening. I think "huh strange." I put a large punch through the comp to get some leverage and I hear BAM!

The pin on the extension sheared and the barrel came loose from the extension. I said "oh my," or something to that effect only more colorful.

Long story short the comp is still frozen on the muzzle, the extension is no longer tight to the barrel, and the pin that locates the barrel in the upper is broken.

Where do I send this thing to to fix it? Putting on extensions etc. is out of my pay grade.

Repairing the index pin is not difficult but it is HIGHLY improbable that anyone will be able to properly torque the barrel extension AND time the index pin with the gas port.

A set of machinists V-blocks is the best method for fixturing a barrel when installing muzzle devices.

The DPMS upper receiver block pictured above and others like it are a terrible design. The clamshell style is the better device for holding an upper for rebarreling.

[Hamma Slamma]

I personally use oak vise barrell vise blocks that I have made. They work excellent and have never scratched a barrel yet. As for the upper vise block I have used tem too, though not the kind postd above. The kind I have fits the bottom side of the lower ont he pins but also fits the picitanny rail allowing you to clamp a little better. This does put alot of stress on the barrel nut though, so the barrel vise jaw blocks do work better for me.