LugerForum Discussion Forums - View Single Post

unspellable · 07-24-2003, 03:56 PM

Bob,

Very good question. This is one of the points of my research into the history and ballistics of the 7.65 mm Parabellum cartridge. I do not by any means have all the answers as of yet, but in the meantime here is some food for thought.

For starters there are far more non-Parabellum pistols chambered for this cartridge than you might think. The earliest such I have come across is at least one C96 Mauser Broomhandle so chambered. Prior to WWI the Italian Glisenti was so chambered. More recently, the Walther P38, the P35 Browning Hi-Power, the Radom, the Colt, and the Ruger P89 have been so chambered.

Prior to WWII the 7.65 mm actually outsold the 9 mm in the US. In those days the Luger was a working gun, not a collector's piece and was quite popular as an outdoorsman's gun for its accuracy and flat trajectory.

I do not have definite proof as of yet, but I believe the US 7.65 commercial loads were hotter than today and were reduced shortly after WWII. Probably due to the influx of war souvenirs and surplus of what was, at least in the eyes of the US ammo makers, questionable quality. Chief offender here was probably the Glisenti, never known for its strength. Around the time of WWI the Italians chambered the Glisenti for the 9 mm Glisenti cartridge. This cartridge is close enough to the 9 mm Parabellum for either cartridge to chamber in either pistol. The Glisenti 9 mm load was mush lighter than the 9 mm Parabellum. During the post WWII period the US makers reduced the load in the 9 mm Parabellum, probably out of fear of the Glisenti pistol.
Since that time the 9 mm has become very popular and the commercial loads have crept back up to their original levels.

The 7.65 was not so popular in the US after WWII and remained in the background with little attention. The post war light loads remained to this day.

I have contacted Winchester about this and found they were not very cooperative. I contacted SAAMI and found they were not very knowledgeable. They could not explain the origin of the SAAMI specs for the7.65 Parabellum. The SDAAMI specs allow an undersized bullet. More importantly they call for a maximum average pressure of 28000 cup. (Or maybe 28400, I am quoting from memory.) This is simply not enough pressure to easily get the muzzle velocity needed to make the Luger function reliably. A Luger with an unusually smooth action or a reduced recoil spring may work reliably with this ammo. I have been learning that cutting the original recoil spring is NOT the proper way to get a reduced recoil spring.

The original DWM loads ran higher pressures and produced higher muzzle velocities. There is nothing about the 7.65 Luger to prevent it from running the same pressures as the 9 mm, and in fact, in the original pre WWI carbine the pressures were higher than the 9 mm. Thus a proper maximum average pressure for the 7.65 really should be about 32000. The proof load ran about 40000 cup for both calibers in the pistol, higher in the original pre WWI carbine which had a max average working pressure on the order of 40000, same as the proof load for the pistol. The carbine load produced a velocity in excess of 1400 fps at 50 feet from the muzzle.
Winchester claims 1220 fps from a 4.5 inch barrel. In actual fact their load will not achieve this velocity form a six inch barrel.

Later I will have a great deal more to say on this subject. The project has been delayed somewhat by an unusually long honeydew list this year.

07-24-2003, 03:56 PM	#15
unspellable User Join Date: Jun 2002 Location: Iowa Posts: 769 Thanks: 0 Thanked 20 Times in 12 Posts	Bob, Very good question. This is one of the points of my research into the history and ballistics of the 7.65 mm Parabellum cartridge. I do not by any means have all the answers as of yet, but in the meantime here is some food for thought. For starters there are far more non-Parabellum pistols chambered for this cartridge than you might think. The earliest such I have come across is at least one C96 Mauser Broomhandle so chambered. Prior to WWI the Italian Glisenti was so chambered. More recently, the Walther P38, the P35 Browning Hi-Power, the Radom, the Colt, and the Ruger P89 have been so chambered. Prior to WWII the 7.65 mm actually outsold the 9 mm in the US. In those days the Luger was a working gun, not a collector's piece and was quite popular as an outdoorsman's gun for its accuracy and flat trajectory. I do not have definite proof as of yet, but I believe the US 7.65 commercial loads were hotter than today and were reduced shortly after WWII. Probably due to the influx of war souvenirs and surplus of what was, at least in the eyes of the US ammo makers, questionable quality. Chief offender here was probably the Glisenti, never known for its strength. Around the time of WWI the Italians chambered the Glisenti for the 9 mm Glisenti cartridge. This cartridge is close enough to the 9 mm Parabellum for either cartridge to chamber in either pistol. The Glisenti 9 mm load was mush lighter than the 9 mm Parabellum. During the post WWII period the US makers reduced the load in the 9 mm Parabellum, probably out of fear of the Glisenti pistol. Since that time the 9 mm has become very popular and the commercial loads have crept back up to their original levels. The 7.65 was not so popular in the US after WWII and remained in the background with little attention. The post war light loads remained to this day. I have contacted Winchester about this and found they were not very cooperative. I contacted SAAMI and found they were not very knowledgeable. They could not explain the origin of the SAAMI specs for the7.65 Parabellum. The SDAAMI specs allow an undersized bullet. More importantly they call for a maximum average pressure of 28000 cup. (Or maybe 28400, I am quoting from memory.) This is simply not enough pressure to easily get the muzzle velocity needed to make the Luger function reliably. A Luger with an unusually smooth action or a reduced recoil spring may work reliably with this ammo. I have been learning that cutting the original recoil spring is NOT the proper way to get a reduced recoil spring. The original DWM loads ran higher pressures and produced higher muzzle velocities. There is nothing about the 7.65 Luger to prevent it from running the same pressures as the 9 mm, and in fact, in the original pre WWI carbine the pressures were higher than the 9 mm. Thus a proper maximum average pressure for the 7.65 really should be about 32000. The proof load ran about 40000 cup for both calibers in the pistol, higher in the original pre WWI carbine which had a max average working pressure on the order of 40000, same as the proof load for the pistol. The carbine load produced a velocity in excess of 1400 fps at 50 feet from the muzzle. Winchester claims 1220 fps from a 4.5 inch barrel. In actual fact their load will not achieve this velocity form a six inch barrel. Later I will have a great deal more to say on this subject. The project has been delayed somewhat by an unusually long honeydew list this year.