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Old November 12, 2012, 10:15 PM   #15
barnbwt
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Join Date: May 17, 2012
Posts: 669
Quote:
Which I think reason enough to stick to SAAMI .45-70 (if it will fit the action).
Or is a 405 at 1700+ insufficient?
Well, it's good to know what the limits of a conversion are, especially when loads are as variable/poorly defined as many of the "modern" .45-70s. I'd hate to rechamber a rifle that could hurt someone with an otherwise safe/common loading. It's comforting to know your 45-70 rifle can also safely shoot full-on 50AK . I'll most likely never shoot the thing anywhere near max simply due to the pain, unless there's a pad out there made of magic or something

At any rate, the reason I opened this thread was to see if I was approaching the bolt-load question from the proper scientific perspective, or if I was totally off base. I appears I'm on the right track; asking the right questions, anyway.

If there is a reliable way to calculate case-friction, someone let me know. I'll bet it's more important in the current chambering at 50,000psi than down around 30000psi, and I need to know if lowering the pressure could actually increase the bolt thrust .

Also, how much force can a cartridge carry before it simply blows out to fill the chamber (stretch or case head separation)?

*Unrelated question: have any of you Contender/Handirifle guys experimented with Sptizer (not rubber-tip FTX) bullets in the 45-70? Does it work, or is performance the same? Would weird barrel twist be needed? I ask because 45-70 is a good deal shorter than the original round, and is in a box magazine; so I'd have more options than the lever guys .
TCB
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