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barrel diameters and muzzle brakes.

 
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  #1  
Old 05-09-2014, 10:22 PM
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barrel diameters and muzzle brakes.

There seems to be a lot of varying opinions on what size of barrel can or can't have a muzzle brake installed.

I am sure some will disagree and that's all right, so hear goes.

After talking to barrel makers and engineers and using there recommendations for MINIMUM wall thickness I found that this was a rule that most were not willing to brake for safety reasons.

After doing all of the calculations using this information this is what I came up with and use for all of my brake installations.

It is based on the caliber of the barrel and safe wall thickness remaining after threading. these dimensions at the muzzle of the barrel are "MINIMUM" for safely installing a muzzle brake.

.224 bore = .563 muzzle diameter
.244 bore = .584 muzzle diameter
.257 bore = .597 muzzle diameter
.264 bore = .604 muzzle diameter
.277 bore = .617 muzzle diameter
.284 bore = .624 muzzle diameter
.308 bore = .648 muzzle diameter
.323 bore = .663 muzzle diameter
.338 bore = .678 muzzle diameter
.350 bore = .690 muzzle diameter
.375 bore = .715 muzzle diameter
.400 bore = .740 muzzle diameter
.416 bore = .756 muzzle diameter
.425 bore = .765 muzzle diameter
.458 bore = .798 muzzle diameter
.470 bore = .810 muzzle diameter
.510 bore = .850 muzzle diameter
.570 bore = .910 muzzle diameter
.600 bore = .940 muzzle diameter

These dimensions are also minimum recommended wall thickness after fluting (Bottom of flute to bore).

There is some support from the muzzle brake depending on the quality of the threads, but I don't recommend relying on the brake to make up the minimum wall thickness. on very small barrels finer thread pitches are normally used because on thread height (The finer the thread the shorter the thread height, using less of the barrel wall thickness.

Also, as bore diameters increase more stress is placed on the barrel because of the larger surface
of the barrel wall.

This post is not intended to be the last word, it is just a guide line to help decide if it is possible to install a muzzle brake safely on your barrel.

Be safe

J E CUSTOM
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Old 05-09-2014, 10:55 PM
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Re: barrel diameters and muzzle brakes.

Good info. Thank you.
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Old 05-10-2014, 09:46 AM
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Re: barrel diameters and muzzle brakes.

This is another excellent info and should be on the "sticky".
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Old 05-10-2014, 09:49 AM
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Re: barrel diameters and muzzle brakes.

J E Custom . I am confused by your post as you do not address thread tenon diameter.are you saying that a 1/2 and 9/16 inch thread should never be used?It looks like your listing minimum muzzle diameter ,are you also saying that this would be your minimum minor thread pitch diameter? in fact 5/8x24 minor pitch diameter is .575 there for anything over.224 bullet diameter would be out.Could you clarify are you saying that you can install muzzle brakes on these diameter barrels, or are these dimensions referring to minor thread pitch diameter.if not what is the minimum thread diameter for caliber?
308nate.
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Old 05-10-2014, 10:12 AM
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Re: barrel diameters and muzzle brakes.

Thanks Jerry. Excellent info.

It's comforting to know you look after these things especially since I dropped off my weatherby earlier this week for bedding and one of your incredible assassin muzzle brakes.
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Old 05-10-2014, 12:00 PM
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Re: barrel diameters and muzzle brakes.

Quote:
Originally Posted by 308 nate View Post
J E Custom . I am confused by your post as you do not address thread tenon diameter.are you saying that a 1/2 and 9/16 inch thread should never be used?It looks like your listing minimum muzzle diameter ,are you also saying that this would be your minimum minor thread pitch diameter? in fact 5/8x24 minor pitch diameter is .575 there for anything over.224 bullet diameter would be out.Could you clarify are you saying that you can install muzzle brakes on these diameter barrels, or are these dimensions referring to minor thread pitch diameter.if not what is the minimum thread diameter for caliber?
308nate.

Yes you can use 1/2'' and 9/16" threads for brakes.

Example = If you have a .224 (223) you would need a .550 barrel diameter to install a 1/2'' 28
break. the minimum I listed was .563 to allow for poor threads or fit.

I use the Minor thread diameter because that is the actual wall thickness to the bore.

The number that engineers gave me was .140 thousandths absolute minimum wall thickness
for fluting at, or near the muzzle and muzzle brake threads Minor thread diameter should not be less.

If you do the numbers, most ARs are marginal with a 1/2x28 TPI thread. .224 bore diameter from
.4768 Minor thread diameter = .2528 divided by 2 you end up with a wall thickness of .1264,you end up with .013 thousandths less than the recomended .140.

This is the case where they are relying on the brake for some support .

The chart I use, takes in to account for as much as can be useful and allows for a fairly safe installation as long as the thread fit is very good.

The size of the thread and pitch is determined after the wall thickness is determined.

All Good questions , And I hope I answered them.

Remember these are my suggestions and if someone wants to deviate from It, That's fine.

J E CUSTOM
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Old 05-10-2014, 12:13 PM
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Re: barrel diameters and muzzle brakes.

Quote:
Originally Posted by matemike View Post
Thanks Jerry. Excellent info.

It's comforting to know you look after these things especially since I dropped off my weatherby earlier this week for bedding and one of your incredible assassin muzzle brakes.


Thanks !

I have some rules of my own and If I don't feel it is safe or the correct way to do it I simply decline

Just because others do something that may be safe, I have to be convinced before I will do it. It does not mean that they are doing anything wrong, I just want to be careful.

Firearms are not forgiving and it only takes one mistake.

J E CUSTOM
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