9 mm Parabellum vs the so called 9 mm Luger

[unspellable]

At the dawn of history, Georg Luger and the boys at DWM created the 9 mm Parabellum cartridge for the Parabellum pistol, popularly known in the US as the Luger.  DWM had various specifications for this cartridge , amoung them a specification for minimum OAL.  So far, so good.

Fast forward to today and buy a box of "9 mm Luger" cartridges.  measure the OAL.  It's less than DWM's minimum OAL.  Look up the SAAMI specifications.  SAAMI's MAXIMUM OAL is exactly equal to DWM's MINIMUM OAL!  This difference is 90% of the Luger's repuation for poor reliability, the ammo ain't in spec!

My question is who, how, when, why, and where did the change occur?  Who was the bright boy who decided to make them too short?

Seems like there ought to be a 9 mm collector out there who can shed some light on this one.

[marlinman93]

Usually 9mm pistols headspace on the case mouth, so oal is not as critical as it would be on a cartridge with a shoulder, or a rimmed cartridge.
 9mm guns that have chambers properly reamed to the exact length of the cartridge used have proven to gain slightly in accuracy, in tests I have seen written up.
 The reason that cases are usually shorter than spec, is to allow for variances between manufacturers. If all were exactly at spec, and all manufacturers were also exactly at spec, there wouldn't be a problem, or any reason to allow for error.
 I know your frustration with 9mm accuracy, as I too haven't seen many guns that would shoot well with factory chambered barrels. I own a S&W model 39 first variation, which is the only 9mm I've ever shot, that would group inside of 2" at 50 ft. That's the only reason I still own it, and have sold all the others I've owned in past years.

[unspellable]

marlinman93,

You have gotten off the track here.  We are not talking about case length, headspace, or accuracy.  We are talking about OAL and and feeding reliability.  The Luger magazine works like a 22 LR magazine and depends upon correct OAL to function properly.  The nose of the bullet must ride on the front of the magazine.  If the OAL is too short the cartridge will rest on the one below it and will be presented to the chamber at an incorrect angle, resulting in a high risk of jamming.  The current factory loads are not just shorter than nominal, they are shorter than the MINIMUM spec.  (Case length is OK, no problem there.)

The SAAMI maximum OAL is identical to the original DWM minimum OAL.  Aside from feeding properly, reducing the OAL increases pressure in a cartridge already operating at a pretty high pressure or if the same pressure is maintained, it reduces the muzzle velocity.

The question remains, who thought up this fiasco?

[marlinman93]

Sorry about that! I did some more researching into my supply of factory ammo, and came up with some interesting (to me) results.
 My Winchester and Remington 115 gr. fmj rounds measure a very short 1.125" oal @, but two other loads from Winchester in a 124 gr. fmj measured very close to specs at 1.150" These two loads were from different eras, and both fmj, with one a nickel case, and the other a brass case. The nickel cased 124's were bought just last year.
 Cartridges of the World lists the OAL at 1.16"

[S.S.]

The original 9mm Parabellum had a truncated cone bullet
of between 123 and 125 grains at approx 1300 fps.
the truncated cone design supposedly made for more
reliable feeding from the mag to the chamber.
The case at first was simply a .30 Luger opened up to accept
a 9mm projectile thus the 9mm Luger name.