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Thread: Crowns

  1. #16
    Join Date
    Dec 2006
    Location
    Branchville, NJ
    Posts
    525

    11 deg. Crown

    There is a theory that was tested that the 11 degree crown works best with the boat tail angle of the Matchking bullets. In all the sniper rifle barrel testing that we have done here, the 11* crown was what has been settled on. Something to do about how the escaping gases act on the bullet. All this has been verified with high speed video at the muzzle. Now we have not tested with flat based bullets, so there might be a difference there.

  2. #17
    Join Date
    Oct 2019
    Posts
    419
    thanks for the DATA..vs opinion.
    now do custom match bullets have the same boat tail angle, and what about rebated boat tail ??

    Quote Originally Posted by MilGunsmith View Post
    There is a theory that was tested that the 11 degree crown works best with the boat tail angle of the Matchking bullets. In all the sniper rifle barrel testing that we have done here, the 11* crown was what has been settled on. Something to do about how the escaping gases act on the bullet. All this has been verified with high speed video at the muzzle. Now we have not tested with flat based bullets, so there might be a difference there.

  3. #18
    Join Date
    Oct 2004
    Location
    Brisbane Australia
    Posts
    156
    Quote Originally Posted by MilGunsmith View Post
    There is a theory that was tested that the 11 degree crown works best with the boat tail angle of the Matchking bullets. In all the sniper rifle barrel testing that we have done here, the 11* crown was what has been settled on. Something to do about how the escaping gases act on the bullet. All this has been verified with high speed video at the muzzle. Now we have not tested with flat based bullets, so there might be a difference there.

    That's very interesting.. Is there any actual data available online on the results? Link? I would be very interested to see it if there is..

    Cheers
    Lee

  4. #19
    Join Date
    Jun 2013
    Location
    North Eastern Australia
    Posts
    223
    Not to diss all the high tech solutions but I once dressed the crown of a .22 RF (because it showed an uneven blast pattern) by using a brass ball in a rotary tool and fine lapping paste. Just enough to obtain a visible bright ring around the bore (probably a few thou). Bore plugged of course.

    It made quite a reasonable improvement to the accuracy according to the owner.

    Btw, I learned of this technique on this site many years ago.

    * doggie *

  5. #20
    Join Date
    Feb 2006
    Location
    Wilcox, PA
    Posts
    672

    Cool

    Quote Originally Posted by rsmithsr View Post
    100 thou is ten time more than the rest of us have stated.
    And no one has endorsed a specific shape of muzzle or proven "best"
    your right.

  6. #21
    Join Date
    Jan 2009
    Location
    Ca.
    Posts
    723
    My own approach for my own competitive cast bullet rifles. Flat with a 30 degee bevel cut to just beyond the bottom of the grooves and then polished. Having tried several others this has worked the best. When cleaning with a wrapped patch it just peaks through the muzzles and I never push it all the way out. The fouling including the primers is actually quite abrasive and if pushed all the way it can start to bell the muzzle. We also have to clean quite allot and one of my barrels and still very competitive now has over 140,000 bullets down the bore and I have only had to re-crown it but once. And right before I retired it, it set a new national record and it has also never been setback but now needs it.

    Last edited by Louis.J; 11-27-2020 at 03:07 PM.

  7. #22
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
    Posts
    6,313

    There was an article

    In PS magazine years ago about crowns where someone did a number of different crowns on the same barrel and if my memory serves, the crowns made no difference in accuracy, even the one hacksaw cut. Suppose it could just have been a great barrel ?

    Pete

  8. #23
    Join Date
    Jun 2014
    Posts
    75

  9. #24
    Join Date
    Oct 2019
    Posts
    419
    my limited knowledge opinion is 1000 yards does not matter.
    do the test at longer range,,,say 300/500 yards.
    me thinks those 100 groups will open up...big time

  10. #25
    Join Date
    Jul 2005
    Posts
    599
    Quote Originally Posted by rsmithsr View Post
    (yes i have a 3 phase motor on my lathe at my house!)
    I had 3-phase with idlers for years.
    Had a neat little starter system to spin up the 3-phase idler.
    Used a rubber tire rubbing on a pulley sheave to spin up the idler.
    Pull lever, enough frictions to get idler spinning.
    Had and indicating system that came on when it was close enough
    in speed to generate decent quality waveforms.

    It is not perfect 3-phase though.
    More like 2-1/2 phase.Two phases at 180 degrees and the middle one between them.

    Switched all but one over to a VFD with 240 V single phase inputs and 3-phase outputs.
    The last one is large enough even a VFD is going to be pricey.

    And I usually only use it for hogging with carbide tooling, then switch to a 3-phase for finish work.

    Doing this saves a decent amount of time on larger items.
    I even did a 3-phase industrial sewing machine for one of the ladies I worked with.
    Linda saw it at auction, called me and asked "Can you make it work?"
    I told her "Not all that hard."
    She bought it at auction.
    Non one else wanted it since they did not know how easy it is to make an idler system.
    Last edited by brickeyee; 11-29-2020 at 05:48 PM.

  11. #26
    Join Date
    Feb 2003
    Location
    Georgetown, Texas
    Posts
    537

    Uneasy lies the head that wears a crown

    How often do you guys re-crown a barrel if at all? Tim

  12. #27
    Join Date
    Feb 2006
    Location
    Wilcox, PA
    Posts
    672

    Cool

    Quote Originally Posted by tim oltersdorf View Post
    how often do you guys re-crown a barrel if at all? Tim
    i once heard g. Kelby say 700 rds

  13. #28
    Join Date
    Jul 2005
    Posts
    599
    Many of the recessed crowns are an attempt to
    minimize the possibility of damage to the actual crown
    in handling.

  14. #29
    Join Date
    Jun 2005
    Location
    Concord,NC
    Posts
    60
    Now how much do you take off of the barrel on a re-crown ? .100 ?

  15. #30
    Join Date
    Oct 2019
    Posts
    419
    i think a lot would depend on the cartridge.
    imho...if the powder burn is complete behind the crown, it will wear less than something that is still burning at the crown
    velocity
    bullet
    powder

    Quote Originally Posted by ArtinNC View Post
    Now how much do you take off of the barrel on a re-crown ? .100 ?

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