This is a very scarce example of a WWII Japanese Type 99 pressure test rifle. These rifles were produced on a very limited basis by both the major rifle factories and were used by the Japanese ammunition factories to test or check rifle cartridge chamber pressures. The general process was to insert a copper cylinder or disc between the upper and lower pistons which would compress during firing. By measuring the compression of the copper, evaluators could get an accurate read on the pressure generated by the shot. This model has the original reinforced chamber with truncated cone at the forward end of the receiver that still has the original pressure test pistons and assembly on top. The left side of the receiver is marked with the intertwined cannon balls of the Kokura factory, and the top of the receiver, pressure chamber and barrel are all numbered "16", with the number "4" on the bolt handle. There are several examples of this type of rifle pictured in Honeycutt and Anthony's book "Military Rifles of Japan" (pages 175-176).