Cartridge Collector > Cartridges > METRIC MILITARY RIFLE > METRIC MILITARY UP TO 5.99mm > 4.2 X 45 FRANKFORD ARSENAL XPL (.16 FA)
4.2 X 45 FRANKFORD ARSENAL XPL (.16 FA)

  

Probably a Frankford Arsenal project from the 1970’s, but very little other info available.