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08-29-2014, 09:11 AM | #13 | |||||||
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08-29-2014, 10:11 AM | #14 | ||||||
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08-29-2014, 10:13 AM | #15 | |||||||
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An equal weight of bismuth to lead is going to have a taller shot column. PS. I am pretty certain Sherman weighed his Bismuth loads, the evidence is the difference in amount of filler wad needed for the same weight loadings vs. lead. |
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08-29-2014, 10:17 AM | #16 | ||||||
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It is ( or should be ) standard procedure to weight all shot charges . Even with lead shot that is a different size or antimony will weigh different if thrown be volume . All shot bushings should be adjusted to throw your shot charges to the correct weight . Thought that was common knowledge.
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08-29-2014, 12:28 PM | #17 | |||||||
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I certainly subscribe to the advice that all should stick to published recipes for bismuth shot by reliable industry sources. |
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08-29-2014, 02:09 PM | #18 | ||||||
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"These constitute the main internal mass [ shot mass ], the internal volume ."
1 oz of Bismuth has more internal volume and mass of 1oz of lead. |
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08-30-2014, 08:46 AM | #19 | ||||||
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I've always thought peak pressure was created within the shot shell , or at most, within the first couple of inches. With that said, Pete's comments about a higher shot column equals more friction, hence higher pressures. Pete also wrote in the Loading the Short 10 on page two :The difference betwen equal weights of Lead vs Bismuth is the height of the shot column and amount of surface area in contact with the bore. 29gr of 7625 is 29gr of 7625. With the lead load you generating 5900 PSI. Nice shot has the same size shot column as lead, but because it's harder than lead it generates more pressure as it has a harder time squeezing down through the forcing cone. This puts you up around 7400 psi with a fold crimp. Using a roll crimp will drop pressure, maybe 600, maybe 800 maybe even a 1000. Only testing will tell for sure. I would stay with the low pressure lead load and add 1500 psi. I can't imagine a sound Parker 10ga having an issue with an 8000 psi load. If you go too low you risk bloopers, especially in cold weather. -- I'm more than happy to agree with " friction in the barrel " meaning " friction in the forcing cone trying to squeeze ".
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Paul Harm |
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08-30-2014, 09:01 AM | #20 | ||||||
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Paul et all,
In a shotshell PEAK pressure is created in the chamber. In a rifle peak pressure is created when the bullet is forced, essentially swagged, into the rifling. When reviewing pressure curves notice that peak pressure of a shotshell occurs early in the curve as measured in time. Remember that the shot column is traveling rather slowly at peak pressure in comparison to muzzle velocity.
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Don't hunt with a gun that will embarrass your dog! USMC Retired USMC Distinguished Marksman USMC Distinguished Pistol Shot NRA Benefactor - Ring of Freedom member |
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