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08-20-2014, 09:26 PM | #3 | ||||||
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pete i thought a roll crimp had less pressure than a 6 point or 8 point crimp..charlie
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08-20-2014, 10:50 PM | #4 | ||||||
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Follow the lead recipe for 1 1/4 oz and take account with additional PSI increase like Pete said. I would not shoot the loads you have that have bismuth since the pressures are unknown.
I have used Long Shot with 1 3/8 oz of Nice Shot #2 for ducks and geese and I believe Pete has it in his 10 gauge spreadsheet. I put a 16 ga. felt wad in the shot cup under the shot for better crimps for this load. Devastating load to feather'ed critters.... http://www.randywakeman.com/Nice_Sho...a_10_Gauge.htm |
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08-21-2014, 11:25 PM | #5 | ||||||
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The only way you are going to know for sure is to carefully load at least 3 shells preferably 5 and send them to Tom Armbrust for pressure testing.
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08-22-2014, 02:26 PM | #6 | ||||||
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I understand that bismuth would have more surface area against the bore as compared with lead (with the same weight/diameter of shot), but why would that result in more pressure? Can you please elaborate? Thank you.
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08-25-2014, 09:52 AM | #7 | ||||||
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I too thought a roll crimp had less pressure than a fold crimp. The depth of a crimp effects pressure whether a fold or roll, so maybe a deep roll crimp would have more pressure than a normal fold crimp. If you're loading at low pressure with normal depth crimps I don't believe it makes much difference which crimp you choose. JMHO
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Paul Harm |
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08-25-2014, 11:18 AM | #8 | ||||||
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Charlie and Paul, what part of my last sentence is/was not clear?
"From what I understand all things being equal a roll crimp reduces pressure 600-800 psi over a folded crimp all else being equal." |
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08-25-2014, 10:41 PM | #9 | ||||||
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i reread this thing 4 times..i dont know where i got this in my head that you said roll crimp was more pressure than 6 point or 8 point crimp..pete plainly states 600 to 800 lbs less pressure with roll crimp...my mistake...charlie
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08-25-2014, 10:53 PM | #10 | ||||||
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Frank, chamber pressure is created by the resistance of the ejecta against being moved forward. Resistance is either + or - by changes in the weight of the ejecta and by changes in the amount of resistance/friction of the ejecta against the barrel wall. An equal weight of Bismuth, say 1 1/4 ounce has a much longer shot column compared to 1 1/4 ounce of lead. (1 1/4 ounce of Bismuth has a little more surface area against the bore than a 1 3/8 of lead.) The larger surface area of the shot column creates more resistance through friction and increases pressure. That is why Bismuth can not be loaded using lead recipes for the same weight with an expectation of similar pressures.
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The Following 2 Users Say Thank You to Pete Lester For Your Post: |
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