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Reloading for 7.7 Japanese
- Thread starter Alfonso
- Start date
The Japanese Model 99 rifles, are very strong. You can load those cartridges up to 308 Winchester pressures if you really want to push the envelope, without any problems. I've done it in the past on a couple of them without any problems at all.
The Japanese, of course, loaded them to around 40,000 psi.
Looking in my personal recipe book, I got the best accuracy out of 56 grains of H4831 under a 150 grain .312 bullet. This load isn't listed in any manuals but it didn't show any pressure signs in either of the rifles I shot them in. This load also, filled the case to the base of the neck. An ideal situation for H4831. I will encouragae caution here. It was safe in my rifles but may not be in yours. As with all milsurps, be very careful. My rifles were in VG+ condition with pristine chrome lined bores and the brass had been fire formed to eliminate head space issues if there were any. From my records, I used a couple of other powders, including IMR 4350 and IMR 4320. The 50 grains of IMR 4320, under 150 grain bullets, produced the highest velocities. About 250fps faster but inconsistent accuracy. I should have played with it a bit more.
My rifles, even though they were in VG+ condition, didn't perform accuracy wise at higher pressures. The H4831 was the most consistent and the IMR4320 wasn't bad at all but not as good. The high pressure loads I tried were safe but accuracy suffered.
The Japanese 7.7 case, has more capacity than the 303 British case and will hold a lot more powder. It is a kissing cousin to the 30-40 Krag cartridge as far as capacity goes. IMHO, in a good rifle, there is no reason the rifle can't be loaded to higher pressures than the manuals reccomend. PO Ackley, tested the Arisaka actions against all of the popular bolt actions of the era. The Arisaka was the only action he couldn't blow up.
The chinese, converted the actions to 7.92x57 Mauser and the US converted them to 30-06 to issue them to Koreans, during the Korean war. If the action wasn't so awkward, it would be up to just about anything you might want to do with it.
The Japanese, of course, loaded them to around 40,000 psi.
Looking in my personal recipe book, I got the best accuracy out of 56 grains of H4831 under a 150 grain .312 bullet. This load isn't listed in any manuals but it didn't show any pressure signs in either of the rifles I shot them in. This load also, filled the case to the base of the neck. An ideal situation for H4831. I will encouragae caution here. It was safe in my rifles but may not be in yours. As with all milsurps, be very careful. My rifles were in VG+ condition with pristine chrome lined bores and the brass had been fire formed to eliminate head space issues if there were any. From my records, I used a couple of other powders, including IMR 4350 and IMR 4320. The 50 grains of IMR 4320, under 150 grain bullets, produced the highest velocities. About 250fps faster but inconsistent accuracy. I should have played with it a bit more.
My rifles, even though they were in VG+ condition, didn't perform accuracy wise at higher pressures. The H4831 was the most consistent and the IMR4320 wasn't bad at all but not as good. The high pressure loads I tried were safe but accuracy suffered.
The Japanese 7.7 case, has more capacity than the 303 British case and will hold a lot more powder. It is a kissing cousin to the 30-40 Krag cartridge as far as capacity goes. IMHO, in a good rifle, there is no reason the rifle can't be loaded to higher pressures than the manuals reccomend. PO Ackley, tested the Arisaka actions against all of the popular bolt actions of the era. The Arisaka was the only action he couldn't blow up.
The chinese, converted the actions to 7.92x57 Mauser and the US converted them to 30-06 to issue them to Koreans, during the Korean war. If the action wasn't so awkward, it would be up to just about anything you might want to do with it.
Any large rifle primer will do. There's data on Hodgdon's site. Hodgdon powders only though.
I have 7.7 Jap data in my old Lyman book too. IMR4064 is given for the accuracy load for a 150. Slug the bore first. Lyman says the barrels can vary from .310" to .317". Most .303 calibre bullets are .311" or .312". Either will rattle down a .314" or .315" barrel. Likely miss the rifling altogether in a larger bore. Steve at .303british.com is, seasonally, making .313 and .314 inch bullets.
Shoot me an e-mail and I'll send the rest of it to you. toheir@hotmail.com
I have 7.7 Jap data in my old Lyman book too. IMR4064 is given for the accuracy load for a 150. Slug the bore first. Lyman says the barrels can vary from .310" to .317". Most .303 calibre bullets are .311" or .312". Either will rattle down a .314" or .315" barrel. Likely miss the rifling altogether in a larger bore. Steve at .303british.com is, seasonally, making .313 and .314 inch bullets.
Shoot me an e-mail and I'll send the rest of it to you. toheir@hotmail.com
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