The Luger was initially designed to chamber the .30 Luger / 7.65mm Luger round.
Later, the Navy, wanting a more powerful "military" class round, requested the 9mm. Modifications were made, but mainly to the barrel and recoil spring.
Remember, for many things Luger the
FAQ document is your friend!
Marc
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Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.