.303 into 7.7?

[A. F Medic]

Can a .303 be fired in a 7.7 jap rifle?

By now, it should be realized that stories about how some military cartridges could be fired in guns chambered for different ones are almost entirely inaccurate. There is no way that cartridges like the .30-06, 7.62 x 54R, 7.62 x 51 or 7.62 x 39 could be fired in the same weapon without at least changing the barrel (and probably doing a lot more in the case of automatic guns). The only partial exception is where cartridges have been given different names in different countries: so the .303" British will chamber in World War 2 Italian and Japanese 7.7 x 56R weapons and vice versa – because it is in fact the same cartridge. However, even then there is no guarantee that automatic weapons will function properly (or that all rounds will be safe to fire in all weapons), as the pressure characteristics of the cartridge loadings may be different.

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[John Sukey (Deceased)]

Actualy the japanese used three different 7.7 rounds. I believe Two rimmed and one rimless. Their supply types must have been tearing their hair out.

The jap Lewis guns used one type, their other machine guns another, and the rifles a third.
I hope I got that right. if not someone will correct me.

[jmoore]

The Japanese Lewis 7.7 IS .303 British. Just not called that so's as to not offend the nationalists of the time, I suppose.

[John Sukey (Deceased)]

And the machine guns in a jap zero were licence built VICKERS

[A. F Medic]

I see what you mean. I just laid Jap 7,7 next to a FN .303 and they really match up. The .303 has a rimmed case though. Thanks again...

[edlmann]

Can a .303 be fired in a 7.7 jap rifle?

The only partial exception is where cartridges have been given different names in different countries: so the .303" British will chamber in World War 2 Italian and Japanese 7.7 x 56R weapons and vice versa – because it is in fact the same cartridge.

Don't know the metric designation of the .303 British round.

The 7.7 Arisaka service rifle round is the 7.7x58, IIRC, and is rimless.

See no way for these to interchange. Only common element is the bore size.

As stated, the Japanese had three different 7.7 rounds in service during WWII, a rimmed a semirimmed, and a rimless.

Hell, they couldn't even get their own ammo to interchange.

The Chinese did convert many of the Type 99 rifles to shoot 7.62x39. These were sold in the U.S. during the mid to late '80s.

[Jim K]

The 7.7 Rimmed IS the .303 British; it was used by the Japanese Navy in license built copies of the Lewis gun and Vickers belt fed machine gun. The former was used in flexible mounts on aircraft as well as being used as a ground gun, the latter was used as a fixed gun on aircraft (Type 89).

The 7.7 Semi Rimmed was used in the Hotchkiss copies fed with stripper clips. Neither the rimmed nor the semi-rimmed will fit in the Type 99 rifle because of the large rims. It is reported that the 7.7 rifle cartridge will work in the Hotchkiss machinegun, but gives malfunctions because the extractor doesn't always catch the rim. Not having one of those machineguns, I can't confirm this.

FWIW, the 7.7 Japanese rimless rifle cartridge will feed and fire in the M1903 Springfield; even the clips will work. The result is a short necked case, but no signs of excess pressure. It will not work in the M1 rifle, because it is pushed too far into the chamber for the firing pin to reach the primer. NOTE: THIS INFORMATION IS FOR DISCUSSION PURPOSES ONLY; I DO NOT RECOMMEND OR APPROVE OF ANYONE FIRING AMMUNITION IN OTHER THAN A FIREARM MADE FOR THAT AMMUNITION.

Jim

[edlmann]

FWIW, the 7.7 Japanese rimless rifle cartridge will feed and fire in the M1903 Springfield; even the clips will work. The result is a short necked case, but no signs of excess pressure.

That would probably work with .300 Savage, .308, etc. The cartridges headspace on the extractor. I've even heard of a .45 ACP round being fired in an '06 this way.

I thought the base dimension of the 7.7 was larger than the .30-06, and that if you rechambered the 7.7 chamber to .30-06, the bases of the fired cases would be swollen. My reloading data shows both with a base dimension of .471, give or take. This was also supposed to be why you should set back the barrel before rechambering to .30-06.

[emmagee1917]

Well...the 06 is .308 and the 7.7 is .311. Close , but there would have to be somewhat of a pressure spike.

As far as a .451 dia .45ACP going down a .308 bore ? Good luck with that. I'll be standing way back to get the good pics , you bet.

Chris

[Jim K]

The base diameters of the 7.7 Japanese rimless and the .30-'06 have a large tolerance overlap, which allows most 7.7 to fire in a .30-'06 chamber and most 7.7 cases made from .30-'06 cases to work without excessive swelling.

Of course, rechambering a 7.7 barrel to .30-'06 itself is not feasible, but a .30-'06 reamer will clean up a 7.7 Japanese chamber. Then if the chamber neck is properly reamed, cases can be loaded with 7.7 bullets. Why was this not commonly done? Because the amount of work that had to be done on the magazine to handle the longer cartridge made it too costly considering the low value of Japanese rifles at the time.

Jim