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Thread: Barrel Crowns

  1. #16
    Join Date
    Feb 2019
    Posts
    677

    No No, Tony

    You opened a dialog on crowns and their importance.

  2. #17
    Join Date
    May 2010
    Posts
    636
    Quote Originally Posted by kevinnevius View Post
    Attachment 25201


    All:

    I have never been a fan of putting anything in the muzzle (even a live pilot). Some of the MI lands offer so little contact for a pilot that I am always worried about marring them. The bullet transition in this area is critical to overall accuracy IMHO.

    I have machined and used small chamfers in my crowns, mostly because I thought it would take cleaning abuse throughout the life of the barrel better, but went away from that also. If you consider it geometrically, any misalignment or minute error in concentricity produces an elliptical edge. Because of that, I have used only offset square cut crowns. Nothing goes into the barrel, and after I indicate in the bore nothing to me is as error free a transition.

    So, I turn for ID to OD concentricity first, then cut as clean a crown as I can - which is very dependent on cutting material / speeds / feeds and lubricant. I use a TIN coated Kennametal insert, in a Dorian positive rake tool holder. I crown at 540RPM, wet with Tap Magic fluid. Not sure if that's optimum, but it has worked well for me in the past.

    The picture is a crown finished last weekend.

    All the very best,

    kev
    OK everyone, you knew I wouldn't be able to stay in the corner long.

    Kev, thanks for posting your approach to barrel crowns. I see you have put some thought into it.

    This approach, executed as you have, should guaranty a great crown.

    Thank you for sharing.

    TKH (4628)

  3. #18
    Join Date
    Jun 2003
    Location
    ohio
    Posts
    64
    Quote Originally Posted by tonykharper View Post
    OK everyone, you knew I wouldn't be able to stay in the corner long.

    Kev, thanks for posting your approach to barrel crowns. I see you have put some thought into it.

    This approach, executed as you have, should guaranty a great crown.

    Thank you for sharing.

    TKH (4628)
    Thanks Tony:

    And thanks for starting the thread. I have to say though, that there is something to the "old" 11 degree crown - some of the best barrels I have had have used this crown.

    What amazes me too (sorry if this is off topic), is how influential crown placement is. I have found that setting back a barrel and recrowning has a huge effect on performance (for example, a .500" setback will IMHO erase any tuning history someone may have acquired with a barrel).

    All the best,

    kev

  4. #19
    Join Date
    May 2010
    Posts
    636
    Quote Originally Posted by kevinnevius View Post
    Thanks Tony:

    And thanks for starting the thread. I have to say though, that there is something to the "old" 11 degree crown - some of the best barrels I have had have used this crown.

    What amazes me too (sorry if this is off topic), is how influential crown placement is. I have found that setting back a barrel and recrowning has a huge effect on performance (for example, a .500" setback will IMHO erase any tuning history someone may have acquired with a barrel).

    All the best,

    kev
    Placement is everything. The crown should be at the roundest, tightest place in the barrel.

    That is very easy to say, and very difficult to do.

    It would be easy if all barrels had a nice taper all the way down, and if they were perfectly round all the way down. But as hard barrel makers try, that isn't always, if ever possible.

    Just think about what is going on when a button is pulled through a barrel. Displacing the metal and expanding it, then the spring back as the button is pulled through.

    Then add to that the fact that our lead bullets are inert. Meaning they have no spring back once deformed. (Paul, if I have mis represented what is actually happening, please feel free to correct me.)

    I think it is a miracle our rifles shoot as good as they do.

    TKH (4628)

  5. #20
    Join Date
    Mar 2013
    Location
    Boothbay Harbor, ME
    Posts
    656
    I tend to think crown placement is more important than the chamber itself.
    When I did my 1st barrel years ago I didn't like how it shot out the gate. I'd bought 3 different reamers so I cut the chamber off & used another reamer & cut 1/2" off the muzzle. The gun then shot well enough & was fairly competitive.
    In hindsight I think the recrowning was the answer but don't know having done both.
    If something doesn't look right out of the gate now, I'll trim the crown before I'll redo a chamber.
    As Tony said, I haven't been able to confidently measure where the tightest or roundest place is.

    Keith
    Last edited by linekin; 01-15-2022 at 07:20 AM.

  6. #21
    Join Date
    Feb 2003
    Location
    Tennessee
    Posts
    6,595
    Before doing any cutting on a new blank, lube and slug it.


    ...

  7. #22
    Join Date
    May 2010
    Posts
    636
    Quote Originally Posted by JerrySharrett View Post
    Before doing any cutting on a new blank, lube and slug it.


    ...
    Great advice!

    Jerry, good to see you post here.

    TKH (4628)

  8. #23
    Join Date
    Oct 2016
    Posts
    64
    We look at the crown as a maintenance item. We keep a eye on them and the rest of the barrel with the bore scope. If they look to be losing their sharpness (from cleaning) Tad will clean them up. Dialing the barrel in takes the bulk of time. Usually it very little removed to sharpen it back up. Carrie and I almost always shoot together and will shoot the same rifle. If its a 6 card match (x2) that rifle will see a cleaning rod in and out 72 times for that match. That rifle will more than likely see a crown sharpening mid season.
    Todd

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