Gunsmithing Muzzle Break Threads?
- Thread starter Brux
- Start date
A lightweight barrel on a .30 call is the riskiest scenario for threading and adding a brake. You don't have enough barrel to go any larger than 1/2" diameter threads because you need a significant shoulder to torque against. If you went with 9/16" diameter threads you wouldn't have much shoulder at all.
The problem with 1/2-28 threads is that the bore to root of the thread is getting very thin. I have done 1/2-28 threads on multiple .30 Caliber barrels including magnums, and have never had a problem, but it sure doesn't give you the warm fuzzies. You risk the muzzle threads separating and sending your brake down range.
You probably would have the least risk with a 1/2-32 thread. The root isn't as deep as a 1/2-28 thread. Vais makes muzzle brakes with 1/2-32 threads and .30 Caliber bore for this type of application. You can also have the gunsmith turn the O.D. of the brake to match the contour of the barrel if you get the brake ahead of time and give it to the Smith when you deliver the gun.
The problem with 1/2-28 threads is that the bore to root of the thread is getting very thin. I have done 1/2-28 threads on multiple .30 Caliber barrels including magnums, and have never had a problem, but it sure doesn't give you the warm fuzzies. You risk the muzzle threads separating and sending your brake down range.
You probably would have the least risk with a 1/2-32 thread. The root isn't as deep as a 1/2-28 thread. Vais makes muzzle brakes with 1/2-32 threads and .30 Caliber bore for this type of application. You can also have the gunsmith turn the O.D. of the brake to match the contour of the barrel if you get the brake ahead of time and give it to the Smith when you deliver the gun.
Also, if you already have a gunsmith in mind to do the work you should call them and ask if they are willing to do it. There are gunsmiths that will refuse to do this kind of thread job because of the issues I listed above.
Had a customer send me that exact rifle along with an APA Gen.1 Micro Bastard (1/2").
Had real reservations about doing it- called APA and spoke with him about it, at least at the time (this was a couple of years ago) they were routinely doing it on their own customs with similar skinny barrel OD's. I did the job, never had any issues after but...really didn't want to take the risk.
As said barrel wall thickness is extremely iffy. Had he not already purchased the brake, my preference would have been (and still is) using 9/16" here.
I'd rather have more meat around the bore to avoid "swelling" which I've seen with really skinny walls. As long as I've got some shoulder to align the brake correctly and use Rocksett or red threadlocker to make sure it can't move.
JMO.
Had real reservations about doing it- called APA and spoke with him about it, at least at the time (this was a couple of years ago) they were routinely doing it on their own customs with similar skinny barrel OD's. I did the job, never had any issues after but...really didn't want to take the risk.
As said barrel wall thickness is extremely iffy. Had he not already purchased the brake, my preference would have been (and still is) using 9/16" here.
I'd rather have more meat around the bore to avoid "swelling" which I've seen with really skinny walls. As long as I've got some shoulder to align the brake correctly and use Rocksett or red threadlocker to make sure it can't move.
JMO.
You can do 5/8x24. You'll need a brake that has an internal flat at the end of the threads. The crown will need to be modified to be flat so the internal flat of the brake can stop on the flat crown, there's your "shoulder" which means the threaded tenon needs to be exactly the length of the depth of the threads on the brake.
I normally do 9/16-24 threads on similar muzzles. I don’t like 1/2 on .30s. You’ll have only about .060 shoulder at 9/16 but it’s enough. If you can shorten the barrel a little bit you’ll get more margin.
On a small barrel or any barrel for that matter, could it be turned parallel and the same in the brake (no threads), then shrink it on with some interference. This would mean a permanent installation for most owners. Or if you don't like this idea, make a threaded adaptor and light shrink fit with Loctite.
LC
LC
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Have you considered a clamp on brake?
https://kahntrol.com/index.php/products-page/clamp-on/ksmb615/
https://www.wittmachine.net/clamp-on-brakes/
https://kahntrol.com/index.php/products-page/clamp-on/ksmb615/
https://www.wittmachine.net/clamp-on-brakes/
I had a customer who ended up with a muzzle break due to the threading on his tiny barrel. We took his .595" diameter muzzle and did a 1/2-28 thread with me warning that it might not hold up. He accepted the risk and had no issues for a bit. On a hunting trip he dropped the rifle and the brake hit something breaking the end of the barrel off. So a real break due to a brake. Might be a bit of an extreme situation unlikely for a target shooter but its something to consider. I won't do any more of them but we do a lot of laughing at threads talking about muzzle breaks. We ended up putting a new barrel on his rifle and it shoots a lot better than it did with the factory job. He is now hunting with a suppressor too so more leverage to break the muzzle off if he drops things. Hasn't broken yet.....
Frank
Frank
