Muzzle brake clearance

J E Custom

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Jul 29, 2004
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10,723
Location
Texas
Muzzle brake clearance . I want to brake my 7mm WSM . Bore in brake measures .330 is that to big ?

It will work but will be less effective than if it were .304 diameter. More gas will exit the front of the brake than normal. Depending on the quality of the brake, it will still reduce some of the recoil compared to no brake at all.

J E CUSTOM
 

Iron Worker

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Apr 3, 2004
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Reno Nevada
It will work but will be less effective than if it were .304 diameter. More gas will exit the front of the brake than normal. Depending on the quality of the brake, it will still reduce some of the recoil compared to no brake at all.
Its a PVA shock wave . I bought this as a improvement over the previous brake. I haven't shot it ,so sure hope they exchange it for 6.5 version and my gunsmith will bore that out.

J E CUSTOM
 

Nieko

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Jan 30, 2011
Messages
115
I like about .030 over, so .314 is what I would go with but give it a try. It may be plenty efficient in 7 wsm depending on brake design. I have found that larger bore in brake makes less difference than I once thought. The standard for me used to be .020 over bullet diameter(.010 per side) but found that an extra .010 worked just as well and less potential for bullet strike.
 

FEENIX

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Dec 20, 2008
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16,410
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Great Falls, MT
Muzzle brake clearance . I want to brake my 7mm WSM . Bore in brake measures .330 is that to big ?

It will work. I have one of Jim See's blast tamer muzzle brakes designed for 7MM-.308 cal ...

ZuytjA4.jpg

bNlQb39.jpg

Have fun with it.
 

Iron Worker

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Apr 3, 2004
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2,243
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Reno Nevada
Well more people are saying its too big rather than saying it will work. Hope Patriot Valley Arms will exchange it for their 6.5 version. My smith will open it up to ideal size.
 

Iron Worker

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Apr 3, 2004
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Reno Nevada
Well more people are saying its too big rather than saying it will work. Hope Patriot Valley Arms will exchange it for their 6.5 version. My smith will open it up to ideal size.
Now on You Tube video a employee of Partriot Valley Arms says "The 30 Cal brake is perfect for the 7mm bore " They've tested it ,I don't want to send it back if its not necessary
 

Vortex!

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Apr 28, 2018
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447
Location
Catlett, VA
I have a 308 muzzle brake on my 270 and it cut the recoil by 60%!! I too was afraid it would be a problem but it works quite well!
 

jimbires

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Mar 16, 2008
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1,942
Location
clearfield county , Pa
I have a couple of brakes from muzzle brakes and more . he has a few videos on his site comparing brakes . read what he has wrote there and watch a few of his videos . in a couple of his videos he says something like in all fairness this test is a little off because I'm testing a properly sized brake to an over sized brake . I'm not sure if these videos are still on there , or if he has put up new ones . they are still interesting to watch . good luck on this .


https://muzzlebrakesandmore.com/testing-videos
 

J E Custom

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Joined
Jul 29, 2004
Messages
10,723
Location
Texas
Durring our recoil test, we tested many things to determine what effects they had on "TOTAL" performance trying to squeeze every ounce of recoil reduction out of a brake.
this was our finding on the bore size issue.

Starting with a bore diameter of .005 larger than the bore to .030 larger we found that there were some very minor accuracy effects with anything smaller than .010. We could only guess that it had to do with the shock wave striking the baffles and bouncing back the bullet off the causing it to yawl. We saw no effect when we exceeded .010.

Note : All test were performed with brakes that were installed on the barrel while still setup and bored to exact dimensions true to the bore. I don't recommend .010 clearance, if it is not installed and bored this way.

As we went up in bore size, we found no change in recoil reduction or accuracy until we reached .020+ depending on the efficiency of the brake recoil reduction began to degrade past .025 to .030.

So we recommend a .020 bore diameter if installed correctly and a .030 for safety if purchased separately.

Any bore diameter larger than .030 only reduces the efficiency of the brake by a measurable amount as it gets larger. We have sense tested brakes for larger calibers and found they were less effective and produced more muzzle flash.

Your .330 bore diameter will be perfectly safe to use so I would recommend trying it first. Without a precise measuring device you may not be able to "Feel" any difference. but there is a loss of efficiency. How much is to much is up to you.

J E CUSTOM
 

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