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AR15.COM
1/26/2012 4:47:50 AM EDT
I have a brake coming that I believe only has a standard .22 cal opening.  The opening will need to be increased to .308.  I have never used a gunsmith before, can anyone recommend someone competent in the ATL for this small task?  I live near the ATL airport, if that helps.

Thanks,

Mark
1/28/2012 6:15:35 PM EDT
[#1]
I'm in Macon.......off I 475....if you can swing by the shop won't take but a minute or two to chuck it up in the 4 jaw and indicate it in........and open it up.......
Rudy

in the phone book as Quality Machine or you can email me at [email protected]
1/29/2012 4:23:26 AM EDT
[#2]
Since you already have a centered hole, wouldn't a common drill press do the job quickly??  BTW, you realize, I hope, that you need to go a few thousandsths greater than the bullet diameter?  
1/29/2012 5:59:08 AM EDT
[#3]
The proper way to open up a brake is to indicate the barrel in the lathe and bore the brake while it is installed on the barrel.  If it isn't installed this way, it should be opened up quite a bit over-sized to accommodate any misalignment.  This will unfortunately reduce the efficiency of the brake.  If there is an extreme misalignment, you may even see asymmetrical compensation, resulting in the rifle recoiling left or right.
1/29/2012 6:44:40 AM EDT
[#4]

I'd chuck it up in a 4-jaw and see how true the insides are vs the OD and then decide from there how to proceed.
1/29/2012 8:55:00 AM EDT
[#5]
With a true thread and a quality brake bored while on the barrel, .020" over bullet diameter is what I consider minimum.  I have seen factory muzzle threads that would require a .050" bore to prevent strikes at the end of the brake.  Concentricity to the threads is the important factor.  Some makers of muzzle jewelry still haven't gotten a clue and thread brakes and cut bores with no reference to each-other.
1/29/2012 10:35:21 AM EDT
[#6]
Quick question.
What .30 cal barrel uses 1/2-28tpi threads at the muzzle?


1/29/2012 11:03:07 AM EDT
[#7]
Thanks everyone.  

Quoted:
Quick question.
What .30 cal barrel uses 1/2-28tpi threads at the muzzle?




None that I know of.  The .22 cal opening is just a default, but the threads are 5/8 x 24TPI.

1/29/2012 4:07:04 PM EDT
[#8]
Quoted:
Thanks everyone.  

Quoted:
Quick question.
What .30 cal barrel uses 1/2-28tpi threads at the muzzle?




None that I know of.  The .22 cal opening is just a default, but the threads are 5/8 x 24TPI.



I thread 7.62 x 25 barrels 1/2 x 28 all the time.......