crown for muzzle break

Discussion in 'Gunsmithing' started by bubba36x, Aug 7, 2010.

  1. bubba36x

    bubba36x Well-Known Member

    Jan 22, 2010
    alright i have a question i have a laith and do all my own machining and im threading my barreel for a muzzle break and i want to know what crown i should use on my barrel
  2. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004
    An eleven degree works well as long as you place it flush with the first port.

    It will be protected by the brake and helps the performance of the brake compared to a
    recessed crown.

    Start inside the bore and come out with a single point tool (Slowly) using the compound
    set at 11 degrees.

    Good luck

  3. specweldtom

    specweldtom Well-Known Member

    Jun 7, 2004
    I think the best crown under a brake is no crown. Just single point the muzzle at 90 deg from the bore out, and don't cut a recess at all. You will either have to always have the brake on (or a nut) to protect the muzzle though. Seems like some brakes want to have the muzzle flush with the back wall of the first chamber, or some want the muzzle slightly in front of the back wall. Either way, it would seem that a perfectly square muzzle would be the most consistent under a brake.

    There are 2 advantages to the 11 deg crown as JE described. First, you would always have a protected muzzle even with the brake off. Second, it makes sense that the slightly obtuse (101 deg) angle makes the edge of the bore resist hot gas and cleaning brush erosion better. You could accomplish the same (or better) bore edge protection by cutting a small chamfer, like factory barrels. I don't do it because I think the perpindicular cut is the most precise cut you can make, and a chamfer isn't.

    I've seen all kinds of crowns on rifles that were extremely accurate, including some with a chamfer cut on them, so this is all just my opinion. Probably any kind of crown that is concentric and true to the bore edge is fine, but to me, the addition of a brake makes it a little more tricky.

    Good hunting, Tom

    GNERGY Guest

    Inside my Muscle brake installed by Jim See, it looks like a 90 deg. cut. Maybe Jim will chime in and tell us his reason for how he crowns the barrels for the brakes.
    I just recrowned my bull barrel 25-06 and did a recessed 90 deg. crown. Now it shoots WAY better. I built this back in 1972 and have around 500 rounds thru it.

  5. Coyboy

    Coyboy Well-Known Member

    Jan 30, 2005
    I usually cut a 90 degree face on the end of the barrel then add a small 60 degree chamfur as the actual crown.

    This protects the delicate edge of the crown from cleaning rod damage. It is more like a small funnel then a 90 degree corner, which can chip or get dinged by the rod or jag, as it is drawn back thru the barrel.

    As long as the bore is dialed in perfect the type of crown makes little difference. Concentricity is the key.