LugerForum Discussion Forums - View Single Post - Why is automatic pistol cartridge case so long?

PhilOhio · 07-01-2009, 11:10 AM

I forgot to mention one important point, regarding the dangerous high pressure spikes which occur with the use of certain types of powders in various cartridge cases when charges are reduced and air space is increased. The best ballistics people, with access to the best laboratory equipment still do not know exactly why it happens. Some have theories, but nothing more. It really is a more complex question than it appears. But I'm a believer and I take their advice.

A. Mifsin,

You said, "...but compressed charge is dangerous on both pistol and rifle..."

My gut feeling is that I agree with you, but sometimes the ballistics professionals do not. Just about all of the reloading manuals list compressed charges for both rifle and handgun cartridges. If their lawyers thought it was unsafe, the recommendations would not be published. But compressed charges make me uncomfortable, and I refuse to load them.

Vlim, Ron, guys,

Yes, there are lots of historical reasons we have cases which are far longer than they need to be, to hold the necessary amount of modern smokeless powder. And in some designs, length helps in feeding and handling of the empty.

But all of the empty space and pressure questions get back to the essential wisdom of never straying from recommendations in the published reloading manuals. In close to fifty years of reloading, I was "forced" (by my own impatience, I suppose) to do it once, in developing a load for an obsolete military automatic weapon for which no such information was available. Nor were the original powder types. I drew upon my own experience, which I thought was pretty extensive, used my own judgment, and relied upon information relating to a nearly identical cartridge used for a nearly identical weapon operating in the same pressure range. I was wrong, and I still do not know why. On the second round, the case head separated. No great damage was done, and I did successfully work up a load, but I was humbled. I haven't strayed from taking my own more cautious advice in the succeeding 20 odd years.

The bottom line is that the science of ballistics is still not a discipline where everything is known about everything. There is no substitute for a laboratory, a pressure gun, good sensors, software, and computer equipment when developing a new load or cartridge type...after all the calculations and predictions have been done.

07-01-2009, 11:10 AM	#13
PhilOhio User Join Date: Apr 2009 Location: Ohio Posts: 145 Thanks: 5 Thanked 17 Times in 14 Posts	I forgot to mention one important point, regarding the dangerous high pressure spikes which occur with the use of certain types of powders in various cartridge cases when charges are reduced and air space is increased. The best ballistics people, with access to the best laboratory equipment still do not know exactly why it happens. Some have theories, but nothing more. It really is a more complex question than it appears. But I'm a believer and I take their advice. A. Mifsin, You said, "...but compressed charge is dangerous on both pistol and rifle..." My gut feeling is that I agree with you, but sometimes the ballistics professionals do not. Just about all of the reloading manuals list compressed charges for both rifle and handgun cartridges. If their lawyers thought it was unsafe, the recommendations would not be published. But compressed charges make me uncomfortable, and I refuse to load them. Vlim, Ron, guys, Yes, there are lots of historical reasons we have cases which are far longer than they need to be, to hold the necessary amount of modern smokeless powder. And in some designs, length helps in feeding and handling of the empty. But all of the empty space and pressure questions get back to the essential wisdom of never straying from recommendations in the published reloading manuals. In close to fifty years of reloading, I was "forced" (by my own impatience, I suppose) to do it once, in developing a load for an obsolete military automatic weapon for which no such information was available. Nor were the original powder types. I drew upon my own experience, which I thought was pretty extensive, used my own judgment, and relied upon information relating to a nearly identical cartridge used for a nearly identical weapon operating in the same pressure range. I was wrong, and I still do not know why. On the second round, the case head separated. No great damage was done, and I did successfully work up a load, but I was humbled. I haven't strayed from taking my own more cautious advice in the succeeding 20 odd years. The bottom line is that the science of ballistics is still not a discipline where everything is known about everything. There is no substitute for a laboratory, a pressure gun, good sensors, software, and computer equipment when developing a new load or cartridge type...after all the calculations and predictions have been done.