My example of this cartridge is headstamped FA 4 06. Specs are:
Rim dia. .526
rim thickness .042
case dia. .470
case length .914
Overall length 1.296
cupronickle jacketed bullet dia. .452

Made only in 1905 and 1906, there were both rimmed and rimless cases.
In Charles R. Suydam's US Cartridges and their handguns it is stated that the charge is 6.9 grains of RSQ powder.

Ken