I know the fact that NO cartridges should be exchanged for another under any circumstances.

BUT I have read somewhere (and I don't remember where and when) that the .303 and one of the several types of Japanese cartridges WERE actually accidentally so close as to be interchangeable.

Is this a FACT or MYTH???

Jean:

The bullets can be interchanged, but not the cartridge. Both are .311 to .313" in diameter. The 30-06 case can be used to form the 7.7MM Jap, but it is slightly smaller in the head dia. than the Jap. The .303 Brit is ..457" case head, and the 30-06 is .470" dia. in the head, and the 7.7s .471" dia. as is the rim dia. while the rim on the .303 is.540 dia.. I doubt that the .303 would chamber and close the bolt over the rim.

The 7.7 Japanese was patterned after the British .303, as far as bore diameter and performance. But in shape, it is like a Mauser rimless cartridge.

To add confusion to all this, I am almost certain that the Japanese military purchased and used light machine guns from the British before the two countries went to war with each other. Therefore, the Japanese used both a 7.7 Japanese (rimless) and a 7.7 Rimmed cartridge, which is basically the .303 british.

I have never tried to chamber a .303 cartridge in a 7.7mm Japanese bolt gun. So I don't know if it will even fit, let alone fire, or be safe.

FACT.

The IJN was patterened after England's RN. If I remember correctly, the IJN had at least one aircraft machine gun that was developed around a Japanese version of the .303. As far as I know, there was never a rifle chambered in the cartridge.

the japanese lewis gun is a 7.7r.it was licenced and made in japan.7.7r is 303 british it uses same drum the parts are close copy.