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Old April 18, 2005, 09:52 PM   #19
Unclenick
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Join Date: March 4, 2005
Location: Ohio
Posts: 10,247
This is an interesting discussion. The acceptable revolver pressures should be theoretically higher than standard .45 ACP pressures simply because the case is completely supported, which it is not in a standard 1911 barrel with no integral ramp. The case head is reasonably strong. The cylinder walls on the N frame revolver will be thinner than on a .44 mag. I would check with S&W on what the limits are, or else pull an Elmer Keith and just slowly work loads up until cases become difficult to extract, then back off a little.

Roll crimps were standard until taper crimp dies were invented. All my old Lyman and RCBS seating dies make roll crimps. Loading jacketed bullets, you just set the die up too high to crimp. 25 years ago a taper crimp die was always a separate operation after seating. Even .45 ACP wadcutters got light roll crimps, but were seated to headspace on the bullet. See an old NRA reloading manual if you don't believe it.

The taper crimp was first sold with the idea that it would let your brass last longer. Failing to crimp cast or lead bullets at all is risky, even for the 1911. Especially with old cases, whose work hardened mouths spring back after sizing and cease to grip bullets firmly. Some of these rounds, with no crimp, have their bullets pushed back into the case on their way onto the loading ramp. This makes for dangerously small powder space and can cause catastrophic pressures.

As for the pin gun load, I would look less to goosing up the ACP than to better bullet shape. Get a mold for a full wadcutter, since the revolver doesn't have to worry about feeding. This will have less tendency to deflect or over-penetrate. NEI's 220 grain .451-220-BBWC looks like a good revolver candidate. They also make 185 and 272 grain wadcutters if you want lighter or heavier weight? They have a 225 grain wadcutter, but its crimp groove is too far forward to leave adequate powder space in the .45ACP case, so I assume it is intended for the post-war .45 Long Colt.

If an indoor range requires enclosed bullets, I would go with the Hornady 230 grain FMJ/FP ENC.

If you calculate maximum loads for different bullet weights with a given powder charged to achieve equal peak pressures, momentum remains pretty constant in the .45 ACP round. You could try lighter bullets at higher velocity to see if they dump the energy any more effectively because their sectional density is lower?

About 5.5 to 6.0 grains of Vihtavuori Oy N330 looks extremely promising for 230 grain bullets in my internal ballistics program. This is seated .265" into a case with 27 grains of water capacity. These charges are within published load specifications, but work up slowly anyway. 900 fps + should result at safe pressures.

Nick
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