 Initially, the Japanese experimented with re-chambering captured American M1 rifles, since the 7.7 Japanese cartridge is dimensionally similar to the .30-06.They found that while the Garand could chamber, fire, and cycle with the 7.7 ammunition, the en-bloc clip system was incompatible with the cartridge and would not feed reliably.Instead the Japanese designers reverse engineered the M1 and discarded the en-bloc clip, replacing it with a fixed internal 10 round magazine charged by two 5 round Arisaka Type 99 stripper clips.