[mrerick]

It all depends on how the pistol is jamming.

Are you experiencing stovepipes? Ejection problems? Extraction problems? In what way is the magazine loose?

While some Lugers are ammo sensitive, they are all a rather precision balanced action. Timing depends on proper operation of many parts including the magazine follower spring, it's latched position in the magazine well, the cleanliness of the extraction well, the ejector and extractor not being chipped, the correct recoil spring and general lubrication and wear.

These are not as forgiving as other later pistol designs.

Addressing these issues sometimes takes a gunsmith with experience in operation and balancing of the Luger's action.