7.7 JAP - Need Some Pointers

[Hanzy4200]

I'm not well versed in rifle casting. I have played with PC .308's, but never used a gas check. I'm getting a type 99 and don't plan on ever buy a factory round, or projectile for that matter. Firstly, what diameter bullet is the norm? The more I read, the more confused I am. Different people seem to shoot them all over the place. As I don't have the rifle in hand, I can't slug. Can I avoid a GC? Will a plain base PC bullet shoot fine with moderate loads? I plan to order a Mold from Accurate. Any style suggestions?


To update from last weeks adventure, I finally nailed down some 8MM Nambu dies, and brass. Will be ordering a 8MM mold along with the 7.7. I'll get these old war trophys roaring again soon.

[415m3]

I cast a 316299 PB and size down to .315 after powdercoating. Still playing with powder but having good results with 18ish grains of 2400. Not using a GC but still accurate and easy enough on the shoulder

[groovy mike]

Use the same projectiles that you would for loading 303 British (at least .310 or bigger).

[Larry Gibson]

Regards 7.7 jap.... I have loaded for 3 of them over the years. Two of them shot the 314299 sized, lubed and GC'd over 4895 with a dacron filler quite well. The third just required a 316299 sized .316 is all. Cases were easily formed from '06 milsurp cases by simply FL sizing in the FL die [FL die adjusted so shoulder of formed case was a tight fit in the chamber] and trimming to fit the neck length of the chamber.

[Hanzy4200]

Regards 7.7 jap.... I have loaded for 3 of them over the years. Two of them shot the 314299 sized, lubed and GC'd over 4895 with a dacron filler quite well. The third just required a 316299 sized .316 is all. Cases were easily formed from '06 milsurp cases by simply FL sizing in the FL die [FL die adjusted so shoulder of formed case was a tight fit in the chamber] and trimming to fit the neck length of the chamber.

I'm going to try for .270 brass. I, like most of us, make good use of as much 30-06 as I can find. .270 on the other hand not so much and I have a hundred or so sitting around. If it's good enough to form 8MM, I expect it can be made to work for 7.7 also.

[JM7.7x58]

My type 99 has a generously sized bore. It slugs at almost .317” I size my bullets to .318. I have had good success with a gas checked Lyman 323470 and the Lee 324-175-1R. I converted Lee to a plain base mold.

I’ve learned that the Metford rifling likes a harder bullet the faster you go.

I either pan lube or tumble lube these, so I’m no help with powder coating.

I use an NOE neck expander (.314” x .318”). It’s not the perfect sized expander, but it works.

JM

[15meter]

I'm going to try for .270 brass. I, like most of us, make good use of as much 30-06 as I can find. .270 on the other hand not so much and I have a hundred or so sitting around. If it's good enough to form 8MM, I expect it can be made to work for 7.7 also.

I use 270 brass where ever possible when doing a case conversion on a .473 diameter case head--I don't shoot a 270, probably never will, by using the 270, I see a 270 headstamp I KNOW it's not a 270.


30-06 stays for the 4 M1's and the 03-A3.

If I used 30-06 for conversions, then it could also be 8x57, 8x60, 7x57, 6.5x55, 318 Westley Richards or a couple of other suspects. Not a good thing.

I see 270 I start being a little extra cautious about which gun it goes into.

I do have the ability to do dumb things. Luckily I've not blown myself up yet.

[Hanzy4200]

I use 270 brass where ever possible when doing a case conversion on a .473 diameter case head--I don't shoot a 270, probably never will, by using the 270, I see a 270 headstamp I KNOW it's not a 270.


30-06 stays for the 4 M1's and the 03-A3.

If I used 30-06 for conversions, then it could also be 8x57, 8x60, 7x57, 6.5x55, 318 Westley Richards or a couple of other suspects. Not a good thing.

I see 270 I start being a little extra cautious about which gun it goes into.

I do have the ability to do dumb things. Luckily I've not blown myself up yet.

I am in the same boat. As I already use .270 to form 8MM Mauser, so I am taking a Dremel and rubbing out the .2 in .270. .270 = 8MM, 70 = 7.7MM