AR 10 Threaded Barrel Problem

[dfletcher]

I have a barrel that is threaded for an AR 10 muzzle device, but the threading job was done so poorly there are high points preventing attachment of the brake I prefer. Some brakes will turn on, some won't - I want the threading to be done right. The job was done out of state, it's not worth it for me to ship the whole rifle (it's an FN SPR) if I can clean up the threading. I thought there was a tool available (thread chaser?) in AR 10 specs (5/8X24TPI) from Brownells, but can't find it. Is there such a tool?

I assume a gunsmith would be able to do the clean up?

[Ryan in SD]

Just get a die and chase em.

Sounds really odd to have high points...must have been really screwed up setup whoever threaded it.

Got pics?

[kcstott]

Easiest way would be to go buy a die
AR die

But unfortunately Brownell's is out of stock.
It is a common thread size so you may be able to go to Sears, Home Depot, Lowes, or someplace like that. Hell Harbor freight would have a kit.

You could also use a thread chasing file. But I would only use one of those as a last resort it's a very crude tool.

[kcstott]

Just get a die and chase em.

Sounds really odd to have high points...must have been really screwed up setup whoever threaded it.

Got pics?

To small of a machine, dull tool, to heavy a cut all could have done it.

[FMJBT]

At MidwayUSA for $29.99.

http://www.midwayusa.com/product/744145/baker-muzzle-threading-die-ar-10-lr-308-5-8-24

I had to buy one a while back to fix the threads on a Black Hole 6.5 Grendel barrel, worked like a charm. You'll need one of these too:

http://www.midwayusa.com/product/395032/baker-die-stock-handle-1-1-2?cm_vc=S015744145

[goober]

yup as said just chase/clean up threads with a 5/8"x24 die
easy peasy

[kcstott]

But on that note. A phone call should be made to the guy that did the work. There is no reason for shoddy crap like that. He will most likely ask for the barrel back to fix it but that just adds to the expense and down time. I'd only send it back it he agrees to do it immediately and pays for shipping both ways.

This is the single reason I started doing my own gunsmithing over twenty years ago. I can't stand crappy work.

[dfletcher]

Thanks guys - that's was I was thinking of, couldn't track it down.

Regarding quality the folks who did the work will get a phone call, it's really the worst I've seen and these guys are pretty high end. The rifle shoots extremely well, they guarantee .3 MOA and definitely delivered based on last shooting session. But the profile on the threaded section looks like Sofia Vergara and that's what causing the problem.

[kcstott]

Never thought a shape like that could be a bad thing but i guess it's only good in certain applications

[SERIAL SNIPER]

thread file

[dfletcher]

thread file

Considered, but it's beyond that. I realize there are "peaks & valleys" measurements in threading, the 5/8X24 is by itself a pretty basic number when it comes to machining. So if all was otherwise OK I'd givethat a try. This is just sloppy work - like someone bumped a machine in mid-thread.

[kendog4570]

What is the major diameter of the thread? (use a micrometer to measure it, not a caliper) It may be interference from the thread crowns touching the brake rather than the pitch diameter. It should be a shade under .625". Sometimes a little "shoeshine" action with some abrasive cloth will fix it up. Or even some careful work with a file.
Do you have a thread micrometer? That will tell you if the pitch diameter is within it's specs.

It is best to try and find out what doesn't fit, before you attemt the fix.

Can you post a picture?