Muzzle brake clearance

Discussion in 'Gunsmithing' started by Iron Worker, Sep 22, 2018.

  1. Iron Worker

    Iron Worker Well-Known Member

    Messages:
    1,871
    Joined:
    Apr 3, 2004
    Muzzle brake clearance . I want to brake my 7mm WSM . Bore in brake measures .330 is that to big ?
     
  2. J E Custom

    J E Custom Well-Known Member

    Messages:
    8,258
    Joined:
    Jul 29, 2004
    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 likes this.
  3. Iron Worker

    Iron Worker Well-Known Member

    Messages:
    1,871
    Joined:
    Apr 3, 2004
     
  4. Nieko

    Nieko Well-Known Member

    Messages:
    106
    Joined:
    Jan 30, 2011
    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.
     
  5. Varmint Hunter

    Varmint Hunter Well-Known Member

    Messages:
    2,745
    Joined:
    Dec 26, 2001
    All my breaks are .020" over bullet diameter. That is what the smiths who installed them recommended.
     
  6. FEENIX

    FEENIX Well-Known Member

    Messages:
    11,010
    Joined:
    Dec 20, 2008
    It will work. I have one of Jim See's blast tamer muzzle brakes designed for 7MM-.308 cal ...

    [​IMG]
    [​IMG]
    Have fun with it.
     
  7. Iron Worker

    Iron Worker Well-Known Member

    Messages:
    1,871
    Joined:
    Apr 3, 2004
    I re-checked my measurements ,its .335 so a .051 over when it should be .020-.030 .
     
  8. Varmint Hunter

    Varmint Hunter Well-Known Member

    Messages:
    2,745
    Joined:
    Dec 26, 2001
    It sounds like it would work great on any 30 cal rifle and still be serviceable on your .284. Dual purpose :>)
     
    Iron Worker likes this.
  9. Iron Worker

    Iron Worker Well-Known Member

    Messages:
    1,871
    Joined:
    Apr 3, 2004
    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.
     
    jimbires likes this.
  10. Iron Worker

    Iron Worker Well-Known Member

    Messages:
    1,871
    Joined:
    Apr 3, 2004
    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
     
  11. Vortex!

    Vortex! Well-Known Member

    Messages:
    268
    Joined:
    Apr 28, 2018
    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!
     
  12. Iron Worker

    Iron Worker Well-Known Member

    Messages:
    1,871
    Joined:
    Apr 3, 2004
    Thank you very much !
     
    Vortex! likes this.
  13. jimbires

    jimbires Well-Known Member

    Messages:
    1,176
    Joined:
    Mar 16, 2008
    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
     
    Iron Worker likes this.
  14. J E Custom

    J E Custom Well-Known Member

    Messages:
    8,258
    Joined:
    Jul 29, 2004
    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