LugerForum Discussion Forums - View Single Post

unspellable · 07-11-2002, 12:59 AM

Yes, a fired case has been stretched. But we are talking about chamber size here, not case size. The first case was a Norinco 7.62 X 25 Tokarev case fired in who knows what. I tried the same experiment with two 9 mm Lugers (A DWM and WWII Mauser.) and a 7.63 mauser case fired in my own C98. Same results. Next I pulled the firing pins and tried an unfired 7.63 Mauser round. Same results. None of them came close to chambering. Next I pulled out the cartridge drawings and it?s obvious the Mauser round will not chamber in a 9 mm. The 9 mm case length is 0.754, while it is 0.761 inches from base to shoulder on the 7.62 Mauser. The 9 mm Parabellum is 0.380 in diameter at the case mouth. The mauser case is 0.397 in diameter at this point and to a distance of 0.007 in front of it. (At least going by the drawings in the Lyman pistol reloading book.) It then angles inward at 16 degrees 24 minutes with respect to the center line. It may be possible to get a 9 mm round to sort of headspace somehow, but not really correctly. Bottom line is, I would not ream a 7.63 chamber out to 9 mm. If I had to make the conversion, I?d sleeve it.

Now as for the derivation of the 9 mm Parabellum. John Sabato puts forth the incentive for doing it, not the actual development process. Now I am not claiming the cartridge derives directly from the 7.65 Borchardt or 7.63 Mauser without the intermediate step of the 7.65 Parabellum, but I am saying the idea merits consideration.

First there was the 7.65 Borchardt. Then came the 7.63 Mauser with no significant dimensional changes, only a hotter load. Then came the 7.65 Parabellum, (circa 1898) a shortened version of the Borchardt. I think everyone will agree up to this point.

The first 9 mm Luger cartridge was DWM case 480, a bottle necked case loaded with a round nosed bullet with a fairly blunt ogive like the 455 Webley auto. The second 9 mm Luger cartridge was DWM case 480A, similar to the first one. The Luger DWM tried to sell to the British military (circa 1902) was chambered for one of these bottle necked cartridges. These cases were longer than the 9 mm Parabellum case (I will use the term 9 mm Parabellum to refer to the final development as we know it today.) These cases have every appearance of being a necked up and shortened 7.63 Mauser case rather than a necked up 7,65 Parabellum case. They do not have the tapered sides of the 7.65 Parabellum and are a bit long for such a conversion. The next attempt was DWM case 480B, a straight case, and as such, outside the entire Borchardt derived family. (Smaller head.) The fourth case, 480C, was a tapered case and became the 9 mm Parabellum. Now it is conceivable that you could neck up a 7.65 Parabellum case to achieve it, but it would be simpler to trim the front off a 7.63 Mauser case and you have the 9 mm Parabellum case with almost no resizing at all. (Keep in mind they all have the same head except case 480B.)

Now speculating as to which led to who is admittedly shaky, we are trying to read the minds of the guys in DWM?s back room a hundred years ago. They would have had all these cases lying about. I?d not be surprised if Georg Luger himself would have difficulty in saying which one led to which. Keep in mind we are not converting brass of one size to another where it?s all clear cut. This is cartridge development with dies for each version and only the head in common, so things are a bit fuzzier as far as saying which derived from which.

Granted, this is all speculation, but that?s where any new hypothesis starts.

One other point, Luger?s magazine design is a bit tricky. If you haven?t noticed, it?s handling cartridges that are longer then the magazine itself is. The cartridges do not stack on each other like they do in most magazines. The rim rests on the case below it while the bullet nose rests on the front of the magazine. They are tilted in the magazine with the nose higher than the base. This trick allows tapered cases, longer cartridges, and the back slanted grip we all love. It?s not so good for feeding hollow points with a big opening and a sharp edge. The edge of the hollow snags on the front of the magazine. But it will handle long cartridges.

07-11-2002, 12:59 AM	#7
unspellable User Join Date: Jun 2002 Location: Iowa Posts: 768 Thanks: 0 Thanked 18 Times in 10 Posts	Yes, a fired case has been stretched. But we are talking about chamber size here, not case size. The first case was a Norinco 7.62 X 25 Tokarev case fired in who knows what. I tried the same experiment with two 9 mm Lugers (A DWM and WWII Mauser.) and a 7.63 mauser case fired in my own C98. Same results. Next I pulled the firing pins and tried an unfired 7.63 Mauser round. Same results. None of them came close to chambering. Next I pulled out the cartridge drawings and it?s obvious the Mauser round will not chamber in a 9 mm. The 9 mm case length is 0.754, while it is 0.761 inches from base to shoulder on the 7.62 Mauser. The 9 mm Parabellum is 0.380 in diameter at the case mouth. The mauser case is 0.397 in diameter at this point and to a distance of 0.007 in front of it. (At least going by the drawings in the Lyman pistol reloading book.) It then angles inward at 16 degrees 24 minutes with respect to the center line. It may be possible to get a 9 mm round to sort of headspace somehow, but not really correctly. Bottom line is, I would not ream a 7.63 chamber out to 9 mm. If I had to make the conversion, I?d sleeve it. Now as for the derivation of the 9 mm Parabellum. John Sabato puts forth the incentive for doing it, not the actual development process. Now I am not claiming the cartridge derives directly from the 7.65 Borchardt or 7.63 Mauser without the intermediate step of the 7.65 Parabellum, but I am saying the idea merits consideration. First there was the 7.65 Borchardt. Then came the 7.63 Mauser with no significant dimensional changes, only a hotter load. Then came the 7.65 Parabellum, (circa 1898) a shortened version of the Borchardt. I think everyone will agree up to this point. The first 9 mm Luger cartridge was DWM case 480, a bottle necked case loaded with a round nosed bullet with a fairly blunt ogive like the 455 Webley auto. The second 9 mm Luger cartridge was DWM case 480A, similar to the first one. The Luger DWM tried to sell to the British military (circa 1902) was chambered for one of these bottle necked cartridges. These cases were longer than the 9 mm Parabellum case (I will use the term 9 mm Parabellum to refer to the final development as we know it today.) These cases have every appearance of being a necked up and shortened 7.63 Mauser case rather than a necked up 7,65 Parabellum case. They do not have the tapered sides of the 7.65 Parabellum and are a bit long for such a conversion. The next attempt was DWM case 480B, a straight case, and as such, outside the entire Borchardt derived family. (Smaller head.) The fourth case, 480C, was a tapered case and became the 9 mm Parabellum. Now it is conceivable that you could neck up a 7.65 Parabellum case to achieve it, but it would be simpler to trim the front off a 7.63 Mauser case and you have the 9 mm Parabellum case with almost no resizing at all. (Keep in mind they all have the same head except case 480B.) Now speculating as to which led to who is admittedly shaky, we are trying to read the minds of the guys in DWM?s back room a hundred years ago. They would have had all these cases lying about. I?d not be surprised if Georg Luger himself would have difficulty in saying which one led to which. Keep in mind we are not converting brass of one size to another where it?s all clear cut. This is cartridge development with dies for each version and only the head in common, so things are a bit fuzzier as far as saying which derived from which. Granted, this is all speculation, but that?s where any new hypothesis starts. One other point, Luger?s magazine design is a bit tricky. If you haven?t noticed, it?s handling cartridges that are longer then the magazine itself is. The cartridges do not stack on each other like they do in most magazines. The rim rests on the case below it while the bullet nose rests on the front of the magazine. They are tilted in the magazine with the nose higher than the base. This trick allows tapered cases, longer cartridges, and the back slanted grip we all love. It?s not so good for feeding hollow points with a big opening and a sharp edge. The edge of the hollow snags on the front of the magazine. But it will handle long cartridges.