7.7 Jap / .30-06 Query

[OEF_VET]

OK, I've heard that you can use .30-06 brass to load 7.7 Jap ammo. Having never heard how this is done, I decided to come to the THR reloading gurus in search of the answer. So, how do you do it? Obviously there are differences in the cases. What is the procedure for making the cases suitable?

Thanks in advance for the help.

Frank

 

[SDC]

Looking at the dimensions in my manuals, it would appear that you'd have to re-size the case bodies, then re-size the necks to take .312" bullets A long process, with doubtless a lot of "oopsies" and wasted cases, and something you'd want to do ONLY if you couldn't get Norma factory brass.

 

[Cortland]

The procedure is actually quite easy and quite cheap. I've done it very recently using Lee dies and case length gauges (both very functional and inexpensive).

First, get your 7.7 jap size die set up in the press. Now, run your .30-06 case through the size die until the going gets tough (that is, the case shoulder makes contact with the die). At this point, you've removed the spent primer and "necked up" from 308 to 312. Now that the neck is expanded, Lee's case length gauge/trimmer will fit in the case. I trim the case way down, perhaps 1/4" from the shoulder. Now put the case in the press again, this time forcing it all the way into the die. Withdraw the case and the case neck will be way too long, trim again and you're done.

I just formed some 7.7 jap case yesterday, but have never fired formed 7.7 cases before. Take out your calipers and you'll note that the base of the .30-06 is indeed smaller than the 7.7. I'm told that when you fire the formed 7.7 cases the first time, you'll get uncontrolled expansion at the base of the case that makes for some ugly buldging. I've heard it recommended that you wrap some scotch tape around the base of the case before the first firing to "take up the slack" in the chamber; supposedly this contributes to more uniform expansion and does away with the buldgy look.

Finally, a formed .30-06 case is by no means a perfect 7.7 case, and I've heard that some people only used the form cases for light cast bullet loads. Then again, Arisakas are known for their strength and I've heard of many people who use formed cases with standard loads with no ill effects.

I'm also told that formed cases won't last as long as true 7.7 cases, but given that 7.7 Jap cases cost a fortune and once-fired 30-06 cases are free pick-ups, I don't find this too troubling.

 

[Paul "Fitz" Jones]

My first reloading business

In high school I had a nightime gunsmithing class.This was in 1951 and I bought a Jap rifle from a veteran for $5 on the advice of my instructor who was also my daytime welding instructor. He said the steel was good and set me up in business. I borrowed a Pacific press and a Jap cut off die from RCBS. I was in the cadet corps rifle team and they had given me a 1,500 round case of GI 06 ammo for pulling bullets and stuffing the cases with cotton for our war games. I popped the neck back with the die, pulled the bullet, poured out the powder, trimmed the neck off and measured 45 grains of powder and replaced the bullet. I then fired them which formed the cases and I reloaded them with 4895 powder with .311 bullets and sold the ammo to pay for reloading tools. When I made The local paper for being the youngest NRA Jr Division DX in the state I was invited to be on the national guard state rifle team and they gave me cases of armor piercing ammo to practice with and I loaded a few thousand 7.7 Jap rounds but the men I sold the ammo to had to have their rifles passed for the quality of the steel by my instructor.. I was in the 1954 State Big Bore Championships and won the hat of Commanding General Hardy my rifle team captain for helping him beat a marine team for the first time ever in the history of the California Guard. I got orders to get out of high school to compete with the Army and Marines at their bases. I was invited with the Guard to Camp Perry but had joined the Air Force by then. My instructor and General Hardy told me the Japanese designed their rifles to fire captured GI ammo and I proved it for myself by forcing an 06 round in and firing it with the rifle tied to a tree.

I was advised that the Jap Arisaka action was one of the best designed and strongest actions made if the quality of the steel was good. The round section of the rear of the action was designed to be able to place the rifle barrel on your boot toe and to insert a GI round and with both hands to be able to force the action shut. The round part was for the heel of the hand to assist in the pushing. I would not use civilian 06 brass only GI 06 for the strength and to withstand the expansion at the base of the case.

John Paul

 

[OEF_VET]

Thanks for the help guys. I knew that if the answer were out there, this would be where it was. I'm not planning to load any '06 converted rounds anytime soon. I just figure that the more you know, the better off you are. You never know when a bit of info might come in handy.

Frank

 

[Cortland]

Took my formed .30-06 => 7.7 Jap cases out today and fired a few. No catastrophic failures.

I tried firing with and without scotch tape around the base -- those with seem to have a slightly more uniform expansion around the case head, but the brass has expanded around the tape's edge towards the front of the cartidge, leaving a very faint shoulder. Not sure if the tape is a good idea or not.

The formed cases were noticeably sootier than my Norma 7.7 cases after firing. Perhaps the formed cases don't get a good seal on the first go-round? I was using a 10% below starting load of BL(C)-2, so that may have played into it. Anyway, between the milsurp BL(C)-2 and the formed cases, I can do some very economical plinking with my Arisaka now

Speaking of economical, I remember reading that someone used .308 projectiles in an Arisaka with "no noticeable decrease in accuracy at less than 100 yards." Anybody tried this?

 

[Paul "Fitz" Jones]

Jap Arisaka

I don't remember the accuracy of the 06 bullets when I fire formed thousands of cases but what concerned me was if the full length 06 case was forced in and the Arisaka owner today has taken off the rear sight. There are the pair of screw holes that held the sight on I seem to remember bothered me that were too deep and close to the bullet of the longer ammo. For customers who wanted to install a scope I felt it could be a problem.

My memory is from 50 years ago.

Fitz

 

[boo586]

I am going to start reloading for my 7.7 jap and I was wondering what powder and loads you guys are using. I will only have access to standard powders (no surplus powders). I will probably use Sierra or Remington bullets of 180 grains. I read that the standard bullet weight was 174 grains for the 7.7 Jap. is this right? Thanks for the help. By the way the rifle was a battlefield pickup that my Grandpa brought home from one of the islands in the Pacific.

Boo586

 

[Cortland]

I load my 7.7s with milsurp BL(C)-2 (primarily since it's dirt cheap from Wideners). I've also used 4895 in the past. Of course you're limited to .311" 303 Brit bullets and I usually use 180 gr. Sierra SPs. Sierra also has 174 gr. FMJ/BT bullets as well, but they're a little more expensive.

My Hodgdon manual lists seven powders with two bullet weights (150 & 180 gr. Sierra SPs) for 7.7 Jap. As long as you follow a manual and your rifle is in verified good working order, I don't think you can go wrong.

My Arisaka came from my grandfather as well -- he brought it back from Okinawa. More of warehouse pickup than a battlefield pickup, If I remember correctly

 

[Paul "Fitz" Jones]

Arisaka Rifles

During the war we deliberately bombed the sources of chromium used to alloy and harden the steel of Japanese weapons so during the production of the Arisaka rifles the quality of the steel steadily declined. My welding-gunsmithing instructor was well aware of that when he set me up with my first reloading business and used a steel Brinell? tester on all rifles of men wanting my ammunition. The poor quality rifles could not stand the pressure of someone wanting to use it as a hunting rifle and were considered unsafe.

This applies to anyone reading this message with a Jap rifle as you could have an unsafe rifle. Later there was a booklet printed deciphering the Japanese symbols on the rifles to read the factory and the date the rifles were made. The date of manufacture was important regarding whether the chromium or whatever other ingredients needed were available when the rifles were made.

The 6.5 rifles were considered fine because of being made before WW2.

Contact the NRA who had information about this problem then and see if there is anyone available to test the quality of your steel before using the rifle.

Fitz