The table you reference contains a well-known error. The third column is actually just a cumulative total of conversions, not serial numbers. If you think about it, converting all those arms in serial number order would have been a logistical nightmare to no practical purpose.


Quote:

Model 1911 Carbines (Karabiner) Converted from Model 1889/1900 Short Rifles and Model 1905 Cavalry Carbines Year      Quantity      Serial numbers [wrong!] 1913      1000      1-1000 1914      8000      1001-9000 1915      8000      9001-17000 1916      8200      17001-25200 1917      900      25201-26100 1918      100      26101-26200 1919      70      26201-26270 1920      65      26271-26335

           
The partial serial given is that of a 1900 short rifle originally manufactured in 1908. The "P64" is most likely to mean "Privatized in 1964". Pictures could assist positive ID.

Nothing unusual.