[mrerick]

The geometry and timing associated with Luger magazine operation is different than in most other Semi-Auto pistols.

This is because of the angle of the grip, and the fact that the magazine had to be designed to fit inside that grip compactly.

For this reason, the overall length of cartridges being correct is critical to the operation of Lugers. Both the 9mm Luger and .30 Luger cartridge use a tapered case body to facilitate extraction. A cartridge with an OAL that is too long or too short will interfere with operation.

The cartridges sit offset to one another with the rim of cartridges in contact with the middle of the body of the next one's case. This can cause the cartridge to cartridge contact point to shift, and the bullet to front of inside of the magazine point to shift in a furrowing direction. That affects timing.

Note that this is quite different than the simpler design of pistols like the P.38 and M1911 and modern pistols with a much more vertical grip.

The hold open operation is activated by the magazine follower button pushing the slide magazine lock up at precisely the right moment before the slide begins to return toward battery. Anything that slows down this will prevent the slide from locking open on an empty magazine.

Dirt in the channel that holds the magazine open lock bar, a weak hold open or magazine spring and delays in magazine timing can all contribute to the failure as mentioned above.