Jap 7.7 Ammo...Safe to Shoot?

[Jeremy]

The Type 92 Hotchkiss MG is said to shoot rimless 7.7 passably well (can't confirm; never tried it), but there is no question at all that it was designed for semi-rimmed cartridges, not rimless. The Type 99 rifle, on the other hand, was intended to be fired only with rimless cartridges, not semi-rimmed MG ammo.

Years ago, a friend who should have known better mailed me some fired cases that he'd shot in a T99 Arisaka rifle, complaining that they were "hard to close the bolt on". Well, of course they were semi-rimmed T92 HMG and were binding on the extractor every time he chambered one. Not only that, but the heads of the cases were swollen and mashed flat from excessive pressure, so badly that if there had been any headstamp there it would have been pressed out. I got on the phone and told him not to shoot any more of that ammo in anything, as the case heads seemed on the verge of bursting. Turned out that he'd removed them from 30-shot Hotchkiss strips, and had not noticed the difference in the rims.

M

,

And yet its perfectly safe to put the T92 powder/projectiles in to new brass and use it in T99 rifles.

[Brewer]

T99 7.7 rimless type 99: 202 gr (13 g) (Ball) 2,200 ft/s (670 m/s) 2,350 ft⋅lbf (3,190 J)
T92 7.7 semi rimmed type 92: 175 gr (11 g) (Ball) 2,440 ft/s (740 m/s) 2,313 ft⋅lbf (3,136 J)

Youtubers results reloading T92 projectile and powder into 7.7 rimless: 2625 ft/s

If its 225 Ft/s faster than what the Japanese intended it to be, perhaps something has happened to that ammo over the last 70 years. Such as the powder breaking down, burning at a faster rate causing higher pressure and higher velocity. Much like that turk 8mm from the same era. When it was made, it produced a specific pressure and velocity. Now 70 years later, the turk 8mm is around 3,000 ft/s and can crack the stocks or worse. Can you put that Turkish 1940s stuff in a Mauser and use it, sure you can. It might go off, is it safe? The issue of storage conditions and time is not native to the Turkish junk 8mm. French, English, German and Japanese surplus ammo is subject to the same issues.
The point is: If some one is going to take the time to reload, then buy modern powder and primers and do it correctly. The components are reliable and not made 70 years ago. Is that t92 stuff safe? It could be, probably, may be but it might not be. Why take a chance on it? Plus in the process destroy an antique relic of ww2.

I'm tapping out. Y'all have a good one, cheers.

[Jeremy]

T99 7.7 rimless type 99: 202 gr (13 g) (Ball) 2,200 ft/s (670 m/s) 2,350 ft⋅lbf (3,190 J)
T92 7.7 semi rimmed type 92: 175 gr (11 g) (Ball) 2,440 ft/s (740 m/s) 2,313 ft⋅lbf (3,136 J)

Youtubers results reloading T92 projectile and powder into 7.7 rimless: 2625 ft/s

If its 225 Ft/s faster than what the Japanese intended it to be, perhaps something has happened to that ammo over the last 70 years. Such as the powder breaking down, burning at a faster rate causing higher pressure and higher velocity. Much like that turk 8mm from the same era. When it was made, it produced a specific pressure and velocity. Now 70 years later, the turk 8mm is around 3,000 ft/s and can crack the stocks or worse. Can you put that Turkish 1940s stuff in a Mauser and use it, sure you can. It might go off, is it safe? The issue of storage conditions and time is not native to the Turkish junk 8mm. French, English, German and Japanese surplus ammo is subject to the same issues.
The point is: If some one is going to take the time to reload, then buy modern powder and primers and do it correctly. The components are reliable and not made 70 years ago. Is that t92 stuff safe? It could be, probably, may be but it might not be. Why take a chance on it? Plus in the process destroy an antique relic of ww2.

I'm tapping out. Y'all have a good one, cheers.

When the data you quote is incorrect from the beginning it means your assumptions based on that are now also incorrect.

JapT99 ammo weights ~182gr not 175gr. T92 velocity is actually higher not sure where your info came from but it's not even close to being correct...and of course it's weight is also off...just not as far.

Turk ammo is SUPPOSED to be around 3000fps as that is what it was designed to do. The only reason it will crack your stock is because your stock was cracked already or you have poor metal to wood fitment.

The point is...if you have piles of this ammo...which there is still a ton of it around and it can usually be found for cheap. Break it down and recycle it. Plus it destroys the whole "you can't shoot MG ammo in a rifle ...too much pressure...blah blah whatever myth"

[bob q]

A Type-99 is just as strong as a 98 Mauser . The 7.7x58 mm is just a 7.9x57mm necked down to 7.7 mm . So any load spec used in a K98k is fine in a Type-99 . Just because a military used a certain load does not mean that is all the rifle could use . The German used four completely different loading , bullet weight and velocity , in the G-98 / K-98 rifles in a 40 year period without changing the rifles at all . That is why you can buy 30/06 ammo with anything from a 110 to 220 grain bullet and shoot it in a M-1903 . The military ammo was dictated by several factors . What dia barrels and bullets they already had tooling to make , what performance they thought would get the job done and useablity . I have used anything from 85 to 215 grain bullets in many Type-99 rifles with no problems . The 85 at 3500 fps is a rip and more accurate that you would think . Also the Turk 154 8mm ammo is a copy of the German S loading , loaded on old German tooling . My original German S ammo has clocked at 2980 from some German Gew-98 rifles . It has nothing to do with cracking stocks , unless you listen to the youtube guys . It has LESS recoil pulse than the later 198 grain load used for years . Cracked stock are caused by loose fitted actions on rifles fired by people who do not know any better .

[Jeremy]

A Type-99 is just as strong as a 98 Mauser . The 7.7x58 mm is just a 7.9x57mm necked down to 7.7 mm . So any load spec used in a K98k is fine in a Type-99 . Just because a military used a certain load does not mean that is all the rifle could use . The German used four completely different loading , bullet weight and velocity , in the G-98 / K-98 rifles in a 40 year period without changing the rifles at all . That is why you can buy 30/06 ammo with anything from a 110 to 220 grain bullet and shoot it in a M-1903 . The military ammo was dictated by several factors . What dia barrels and bullets they already had tooling to make , what performance they thought would get the job done and useablity . I have used anything from 85 to 215 grain bullets in many Type-99 rifles with no problems . The 85 at 3500 fps is a rip and more accurate that you would think . Also the Turk 154 8mm ammo is a copy of the German S loading , loaded on old German tooling . My original German S ammo has clocked at 2980 from some German Gew-98 rifles . It has nothing to do with cracking stocks , unless you listen to the youtube guys . It has LESS recoil pulse than the later 198 grain load used for years . Cracked stock are caused by loose fitted actions on rifles fired by people who do not know any better .

Bingo!!



Some Turk ammo myths busted right here!