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PostPosted: Sun Sep 30, 2018 7:55 pm 
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Has anyone ever read anything about how much pressure their loads generate in PSI?

I got this from a collector in Europe today:

"The original M1870 cartridge used a lead bullet weighing 20 grams - this equates to 309gr but I have seen it listed by several sources as 313gr. The powder charge was 4 grams of fine blackpowder for rifles and 3.5 grams for carbines. Muzzle velocity figures are stated as 1350 fps for blackpowder loads and 1420 fps for ballistite loads.

The later M1890 cartridge used a jacketed bullet weighing 245gr (15.9 grams). The powder charge was 2.4 grams of ballistite. There was no special loading for the cavalry carbines as these were only intended for issue with the infantry rifles. The only velocity reference I’ve seen for this load (despite it being the most prevalent) is 2000 fps. Most references cite the jacketed bullet as being the same weight as the lead bullet and thus give the same velocity figures."

I have researched a load on Quickload and determined that a load with about 14,000 PSI will launch a 240 gr bullet at 1907 FPS.

I would feel much better about this if I could figure out what the design of the rifle is designed to handle but then again in 1873 I suspect they didn't know how to measure or calculate pressure.


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PostPosted: Sun Sep 30, 2018 8:26 pm 
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Теперь предлагаем бесплатную ежедневную маммографию!
Теперь предлагаем бесплатную ежедневную маммографию!
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Joined: Sun Aug 05, 2007 9:04 pm
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Location: On the couch a lot now that I'm retired
I doubt the copper pellet crusher was invented then. I'm not even sure how they measured velocity. SW

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PostPosted: Mon Oct 01, 2018 6:29 am 
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PFC
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Joined: Mon Aug 13, 2018 11:12 am
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I am afraid you are right. I wish I had a new striker spring for mine. When I get up to 22 grs of 2400 the pressure inside the case wants to reverse flow and striker backs up. That is supposed to be just shy of 13,000 psi and sonic but I am not getting the sonic signature. I need to set up my chronograph and check things out better.

I have had the same reverse flow thing in a Rem 7615 rifle shooting MILSPEC ammo. I changed the hammer spring ( new from Wolff Spring) and the problem went away immediately. I have done the same thing in Mod 70 Win.

5.56 MILSPEC has a very hard primer and is not supposed to reverse flow at all but will if non milspec primers are loaded.

I have not been able to find a propellant burning rate chart showing where Ballistite is published.


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