Given that the barrel will be approximately .700" at the muzzle and is 308 cal. and chambered for 300 WM, what size threads should be used on the muzzle? My thought is that 5/8"-24 is appropriate. That leaves plenty of metal around the bore and a 0.037" shoulder to tighten the brake to. Sound right? I'll be using a Schuler brake and wonder if the .875" or 1" dia. brake be best?
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Gunsmithing Muzzle Brake Thread Size
- Thread starter CNJarvis
- Start date
I would do 9/16x24. .037" for a shoulder is pretty thin and it would be less if you relief cut the threads on the brake if the threads don't have it. I'd do a .875" brake turned to .800 and tapered to .700" with 9/16x24 threads.
I would think 5/8x24 would be fine. Yes turning the brake down can effect it's performance. Some guys like it to blend into the barrel diameter. I would suggest having a bevel turned onto the brake at the back of the brake tapering to the barrel. This will give a better looking transition from brake to barrel. Also I would recommend a brake with a clamp on style for the barrel you have quoted.
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5/8 will be fine and it is more meat around the crown that is a critical area to accuracy (crown swelling)
Might want to consider this: A brake that also clamps that are some of the best anyway. (AI, badger).
Or find a collar or washer that fits the .075 difference tightly that is more than plenty. but try the
brake first as it might not be needed.
In some situations I have done a custom thread at the full diameter and then opened up the brake thread to match.
A stop collar is easy. but not really 100% needed if you do not have the tools or means.
Might want to consider this: A brake that also clamps that are some of the best anyway. (AI, badger).
Or find a collar or washer that fits the .075 difference tightly that is more than plenty. but try the
brake first as it might not be needed.
In some situations I have done a custom thread at the full diameter and then opened up the brake thread to match.
A stop collar is easy. but not really 100% needed if you do not have the tools or means.
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Because you are not putting the threaded shank in tension. Too much tension and you stand the possibility of distorting the bore slightly.
I have a customer that insist's I barely overtime a brake. When he does the final installation he Loctites and times it 12:00.
He wants no tension on the shank.
He swears that he can tell a difference between a torqued brake vs the non torqued one.
What others said there is no need to put tension on the extension and also indexes perfectly and easily and will never move.
That is how the AIs and other top performers are delivered.
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I would not think that with 10-32 clamping screws you could generate enough pressure to constrict the bore.
They will pop the heads off long before that (I know this to be true, I have had more than a few guys bring in rifles with snapped screws. Left handed drill bits are a Godsend).
Much more than 25 in/lbs will snap the heads off.
Far easier to stretch a thread than to collapse a heavy walled cylinder.(which is what a barrel is essentially)
A good example on fastener stretch- rod bolts on engines are now torqued to stretch specifications rather than a torque value.
And on the other hand, I've seen far more choked bores due to over tightened clamp on style brakes than I have from properly timed simple thread on brakes.
You don't have to turn it down. Some people just like brakes to be as close to the barrel OD as possible. Taking .037" off each side won't do much to the recoil reduction.
The odds of a brake being out of alignment with the bore will go up with a clamp on compared to a brake that tightens on a square cut shoulder. Another problem with running .037" or less of a shoulder is the brake will tend to go from timed to over timed when taking it on and off over time. The less shoulder you have the more rapidly this happens.
Clamp ons with the bulky clamps are cheesy looking to me. A professionally fitted and contoured brake looks much cleaner.
Here is one I just made for a .17 Hornet. I couldn't find anything with a .197" bore in it so I had to make one. First 17 Hornet that ever fit right and the recoil reduction is much better than putting a 22 sized brake on it.
Here is the plain CSR installed.
And Darrel Holland's newest design.
An old Vias turned flush.
Here is one I just made for a .17 Hornet. I couldn't find anything with a .197" bore in it so I had to make one. First 17 Hornet that ever fit right and the recoil reduction is much better than putting a 22 sized brake on it.
Here is the plain CSR installed.
And Darrel Holland's newest design.
An old Vias turned flush.
The clamp on are threaded before they are tightened. No much tension is needed and easily removable for cleaning and will index perfectly no matter how many times is taken off.
And they will not walk/move. This is a fact not an opinion.
However based on the thin barrel contour here there is a good reason to consider a brake as light as possible.
Probably a short one with one wide baffle cut will give the best balance between size, mass and effective recoil reduction.
Might want to consider the FTE mini or also a custom job.
Badger mini.
Brakes with small cuts and ports and exotic patterns are cool but rarely efficient.
The directives here have not changed in the last 100 years whether one talks small arms or howitzers.
And they will not walk/move. This is a fact not an opinion.
However based on the thin barrel contour here there is a good reason to consider a brake as light as possible.
Probably a short one with one wide baffle cut will give the best balance between size, mass and effective recoil reduction.
Might want to consider the FTE mini or also a custom job.
Badger mini.
Brakes with small cuts and ports and exotic patterns are cool but rarely efficient.
The directives here have not changed in the last 100 years whether one talks small arms or howitzers.
Clamp ons with the bulky clamps are cheesy looking to me. A professionally fitted and contoured brake looks much cleaner.
Here is the plain CSR installed.
The lower brake in the photo above is what I'm going for. Schuler's brake will do what I want it to do at half the price of most other brakes I've seen and by all accounts I've read, quality and performance are excellent.
Thanks to all for your input!
I like Ross's brakes but learned it's best to get them as a blank. He can thread it but don't have him bore it or taper it. That way your installer can contour and bore it in line with the threads.
I understand not having it tapered or at least having it tapered slightly over barrel diameter at the muzzle end but not having it bored puzzles me.
If the barrel threads are concentric to the bore and the bored holes in the brake are concentric to the brake's threads, what's the issue? I'm assuming that the boring and threading operations occur on the same setup.
A large part of the attraction of the Schuler brake is that it's ready to install without additional 'smithing.
If the barrel threads are concentric to the bore and the bored holes in the brake are concentric to the brake's threads, what's the issue? I'm assuming that the boring and threading operations occur on the same setup.
A large part of the attraction of the Schuler brake is that it's ready to install without additional 'smithing.
You need to synchronize the threads to come to a perfect stop (indexed) when properly torqued.
you either machine that together so the machinist can match that or they will send the brake to put an index mark before the ports and finishing cuts.
...or also, in the absence of clamping, then use collars or cut from the stop end after the ports are cut. all basic machining considerations.
The above design is good and should perform nicely. If this can be customized consider a lower mass shorter and slimmer dual baffle brake due to your thin barrel.
Just something to think about.
you either machine that together so the machinist can match that or they will send the brake to put an index mark before the ports and finishing cuts.
...or also, in the absence of clamping, then use collars or cut from the stop end after the ports are cut. all basic machining considerations.
The above design is good and should perform nicely. If this can be customized consider a lower mass shorter and slimmer dual baffle brake due to your thin barrel.
Just something to think about.
That is the problem. They are threaded after thy are made with a tap. Not sure if they are hand held or he is using a floating holder in a tailstock but they can be off pretty good. You can see the 3 jaw prints in it. They are not even a little straight. Once in awhile you get lucky and get one close. When you thread one on I have had the body and the bores wobbling around with as much as .025" runout. I have to turn the out side and recut the bore to bring them in line with the threads. I don't charge extra for it. It's all part of fitting a brake.
For a little more the CSR runs true as can be and a lot less work to install because I don't have to remachine the whole thing.
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