Joe,
The key piece to putting a date estimate on this gun is whether the gun bears the "early" or "later" Lindner marks. Both marks will be found in the same spot - on each barrel just ahead of the barrel flats. The early guns (pre-1892) will have the early Lindner mark (crown over crossed pistols) while the later guns will bear the initials HAL over the same crossed pistols.
More than likely this is a later gun in which case the serial number would put its manufacture at circa. 1910/1911. I would expect the gun to have 1892 German proof marks, but not 1912 nitro proof. It should also have sideclips and a country of origin marking ("PRUSSIA").
Ken
