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unspellable · 08-08-2002, 09:12 PM

In some cases it doesn't take much to do it!

For the 30 Luger, the Winchester handloading guide lists 4.2 grains of 231 at 1085 fps from a 4.5 inch test barrel as running 25,500 CUP and calls it a maximum load. This is well under even the low SAAMI maximum pressure. I started wondering why such a light load and ran some calculations.

Admittedly, this is an "on paper" calculation, but if we up it 0.1 grain, usually the smallest increment a handloader will use, we are over 28,000 CUP, and at 4.4 grains we have reached 28,542 CUP, over the SAAMI maximum. Now you better believe Winchester will observe the SAAMI maximum even if it is low. But the point here, is that we have a case where a very small increase in powder charge drives us from a low pressure to over maximum and the middle ground went by too fast to notice if you blinked.

Just for laughs, a double charge, (Don't know if it would fit in the case or not.) would produce a muzzle velocity of 4340 fps provided the gun stayed together long enough for the bullet to reach the end of the barrel. This seems extremely unlikely as the pressure when the bullet has traveled less than an inch would reach 408,000 CUP. It would make a genuine collector's piece out of the gun. I would want at least thirty feet of string for pulling the trigger. This kind of pressure would be hand grenade country if the gun stayed together long enough for the pressure to get that high. Actually, I would expect the gun to blow before it got past 100,000 CUP which explains why blowups usually (Note: usually...) don't kill the bystanders outright. I am talking an out and out blow up here, not split cases, blown primers, or busted extractors and breechblocks that happen at pressures below 100,000 CUP.

08-08-2002, 09:12 PM	#2
unspellable User Join Date: Jun 2002 Location: Iowa Posts: 769 Thanks: 0 Thanked 20 Times in 12 Posts	In some cases it doesn't take much to do it! For the 30 Luger, the Winchester handloading guide lists 4.2 grains of 231 at 1085 fps from a 4.5 inch test barrel as running 25,500 CUP and calls it a maximum load. This is well under even the low SAAMI maximum pressure. I started wondering why such a light load and ran some calculations. Admittedly, this is an "on paper" calculation, but if we up it 0.1 grain, usually the smallest increment a handloader will use, we are over 28,000 CUP, and at 4.4 grains we have reached 28,542 CUP, over the SAAMI maximum. Now you better believe Winchester will observe the SAAMI maximum even if it is low. But the point here, is that we have a case where a very small increase in powder charge drives us from a low pressure to over maximum and the middle ground went by too fast to notice if you blinked. Just for laughs, a double charge, (Don't know if it would fit in the case or not.) would produce a muzzle velocity of 4340 fps provided the gun stayed together long enough for the bullet to reach the end of the barrel. This seems extremely unlikely as the pressure when the bullet has traveled less than an inch would reach 408,000 CUP. It would make a genuine collector's piece out of the gun. I would want at least thirty feet of string for pulling the trigger. This kind of pressure would be hand grenade country if the gun stayed together long enough for the pressure to get that high. Actually, I would expect the gun to blow before it got past 100,000 CUP which explains why blowups usually (Note: usually...) don't kill the bystanders outright. I am talking an out and out blow up here, not split cases, blown primers, or busted extractors and breechblocks that happen at pressures below 100,000 CUP.