1911Forum - View Single Post - Hey Steve! (in Allentown), What about 9's & 10's?
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Old 01-22-2020, 03:38 PM
Steve in Allentown Steve in Allentown is offline
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Join Date: Sep 2010
Location: Allentown, PA
Posts: 1,971
Originally Posted by Jolly Rogers View Post
Why would case length matter? Rim thickness from base to extractor grove should be the determining factor.
Here are the optimum hook-to-breechface distances provided by log man:
  • 9mm - .060"
  • 40 S&W - .065"
  • 45 ACP - .075"

Here are the SAAMI specs for rim thickness from base to extractor groove:
  • 9mm - .050"
  • 40 S&W - .055"
  • 45 ACP - .049"

I'm not seeing the correlation between rim thickness and hook-to-breechface distances. That distance may be more of a function of the angle at which the rim begins moving up behind the extractor. That angle would be influenced by the length of the cartridge. I'm just speculating here. Where are the engineers when you need them?
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