Hi Jim,
Early original Navy Lugers have a 6" barrel, and as Tac says, a two postion Navy rear sight. They also have a large flanged toggle pin.
Weimar Navy (post WWI) Lugers are reworks of early Navys. Barrel shortened to, or replaced with a 4" and in most cases with a conventional rear toggle link, with standard rear sight replacing the 2 position sight , sometimes retaining the original Navy proof/accptance marks. Most often property marked with an N(Nordsee station) or O(Ostsee station) followed by a property number on the grip strap. May have an Eagle M with or without an Anchor on the grip strap.
Third Reich Navys may have the N and/or O property mark, and/or Eagle M. As WWII began and progressed, these marks were often not applied.
This is an Weimar reworked 1917 Navy. Note the Crown M Imperial Navy acceptance stamps on the receiver.
The property mark.
