This is a very rare example of a Japanese Type 38 pressure test rifle. Which is uniquely chambered in 7.7mm caliber (not 6.5mm as the model would suggest!) 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. Based on the amount of resultant deformity of the copper crusher (how much it flattened out) that reading would translate to a pressure level on a triage table that would indicate if the rifle ammunition was being produced to the correct pressure and velocity levels. This model has the original reinforced chamber and 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 on the top of the receiver, the pressure chamber is numbered "6" vertically on the rear flat and the bolt is not numbered. There are several examples of this type of rifle pictured in Honeycutt and Anthony's book "Military Rifles of Japan" (pages 175-176).