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shell crimping

Discussion in 'Reloading' started by Hinch, Jan 8, 2017.

  1. Hinch

    Hinch Active Member

    Feb 19, 2015
    I don't know if this was ever brought up.I was wondering if when you are reloading shotshells does the crimp affect the pattern in any way if some of the crimps are not uniform?
  2. Bob_K

    Bob_K Well-Known Member

    Jan 29, 1998
    Afton, Virginia
    The answer is potentially. The crimp initially retards the movement of the wad and shot, promoting an efficient burn of the powder. Studies of how many times a hull can be reloaded generally show a decrease in velocity as the hull wears, particularly at the crimp area. Patterns are affected by the initial velocity. I suspect a crappy crimp will have a similar affect as a worn crimp. Variation in crimp depth can also affect patterns due to varying pressures. From Bob Brister's studies, for two shell of equal velocity, the one with the higher pressure will tend to have a more open pattern. For two shells of equal pressure, the one with the higher velocity will tend to have a larger pattern.
    Hinch thanked this.
  3. Jeff.Buchheit

    Jeff.Buchheit Member

    Nov 15, 2012
    I never took it to chance. If the shell comes out with a not so perfect crimp, it gets marked with an X on the bottom, put and put in a box marked for practice only.
    Geoman15 and Mike Hessong* (MH*) thanked this.
  4. Nebs

    Nebs Well-Known Member

    Sep 7, 2012
    Annapolis, MD