Do bottleneck cartridges increase pressure?

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dgang

Bearcat
Joined
Jun 29, 2009
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Colorado Springs
Wanted to ask a question that puzzles me. Do bottleneck cartridges increase pressure? I can load 22gr. of H110 under a 110gr. bullet and achieve about 35,000 PSI. However, if I load 22gr. of H322 in a .223 case under a 69gr. bullet I'm loading about 55,000 PSI. Why does a smaller case (.357) with a much faster powder and a heavier bullet result in less pressure? I was told that a bottleneck cartridge does not increase pressure. What goes?
Thanks in advance and good shooting' to ya, Dgang
 
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Could it be the percentage of empty space is higher in the 357 case, therefore more room for gas expansion before pressure starts to rise?

Not very much empty space in a bottle neck rifle cartridge after the powder is dropped.
 

Chuck 100 yd

Hunter
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Mar 20, 2010
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Ridgefield WA
Assuming equal case volumes and powder charges , the round with the larger bore will run at lower pressures because as the bullet travels down the barrel there is more room for gas expansion.
Large powder charges behind a small diameter bullet gives higher pressures.
 

woodperson

Single-Sixer
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Sep 27, 2004
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I think pressure is more a function of powder charge and bullet weight and less of case design. You can load to maximum allowable pressure with any case design.
 

grobin

Blackhawk
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Mar 8, 2016
Messages
846
Chuck gave the major factors. If there were identical cartridges one with a bottle neck and one without, the bottle neck cartridge would produce slightly higher pressures. You are forcing the same volume of gas through a relatively smaller opening.
 

wwb

Hunter
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Nov 18, 2004
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wisconsin
woodperson said:
I think pressure is more a function of powder charge and bullet weight and less of case design. You can load to maximum allowable pressure with any case design.
Sorta..... powder burn rate and caliber are factors as well. For bullets of the same weight, the smaller caliber will require a higher pressure to achieve the same velocity as the larger caliber.
 
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