Wednesday, November 23, 2011

How to make your own 7.7 Jap rifle ammo

This article should be of interest to certain historical rifle shooters. It covers how to make ammunition for the World War Two Japanese rifles chambered for the 7.7x58mm round. This would be the Type 99 Arisaka rifles that are still somewhat common out there, both sporterized for hunting and stock collectibles. Here's mine. I've had it about thirty years but it's basically been a wall-hanger/safe queen for lack of ammunition since the US military pretty much put the Japanese ammo plants out of business in 1945. Today, the gunwriters tend to call the cartridge that it fires "7.7 Arisaka" or just 7.7x58mm. Back when I was growing up we always just called it "7.7 Jap" and the rifles were always "Jap rifles" regardless of the actual make or caliber. Now this may offend some of the more PC individuals out there, or possibly the Japanese, but you know what? We won that war so we'll call it whatever we like.

Anyway, if you have one, you'll know that ammo's tough to come by and expensive as hell. Only a couple of companies make it commercially now and it's spendy stuff. If you're just going hunting and only need 20, you might not mind dropping $30-$40 for a box of 20 rounds. But for target shooting or plinking? That's pricey range fodder.

So here's an alternative that many people use, me included.

Start out with a .30-06 case, commonly available pretty much anywhere.

I put mine in this low-tech but effective fixture made of nails pounded into my workbench. It holds the case with the neck over the edge of the bench, as shown.

Next, we call over Mr. Dremel and knock about half of the neck off above the bottleneck. Gauge used: Mk I eyeball.
This is what you want:
Measurement's not a big deal at that stage because you're just taking off excess metal before trimming to size using the case trimmer.
2.27 inches will do you just fine per the Lyman and other reloading guides.
Now after beveling and chamfering the case mouth, you lube that case and run it through the 7.7 resizing die. This sets the original neck back about .130 inches and expands the case mouth from .308 to .311.
Prime your case and charge it with whatever powder you fancy. This batch is getting Win 748 just because I've got a pound lying around. Then seat your bullet. Here again, you can use cheap 7.62x54mm (Russian) pull-down pullets because they, like the 7.7 Jap, and the .303 Enfields, are .311 diameter. Or if you want to tighten it up a bit, Hornady makes a killer .312 round nose soft-point. My Enfields love those.
Keep your overall length under 3.15 inches and any rifle your loading for should chamber them easily.
Finished product below: One round of 7.7 Japanese.
Here's twenty newly-minted rounds. Took me about an hour, but I enjoy time at my loading bench so it's all good. These particular rounds will actually go to another blogger that some of you follow. She also has a Type 99 Arisaka that she inherited. These are loaded light because I suspect that hers hasn't been fired since shortly before Douglas MacArthur sailed into Tokyo Bay.
And by way of comparison, one of the new rounds (left) next to the .30-06 that the case started out as. Not really much of a difference, eh? Just shorten the case, move the neck back, and expand the case mouth. Simple really. And it beats hell out of paying for store-bought.

10 comments:

  1. Thankfully, moving the mouth diameter up by a few thousandths doesn't result in any neck thickening (except for the wall taper).

    I bought a Remington 600 a few years ago from a guy, complete with a coffee can of reloads, necked down from .308 to .243. The recipe card was in the can and appeared to be within the envelope of my reloading tables, and inspection indicated he'd taken the time to bevel the case mouths and apparently turn the necks a bit. What I believe he didn't do was to properly anneal the necks first, as most showed signs of incipient neck cracks.
    In any event, they've provided excellent plinking and even sighting-in rounds, even though they can't be again reloaded.

    Because of the ubiquity of .243, though, I don't see myself making any more that way. (Full disclosure: In my younger days, I re-formed several dozen surplus 5.56 to .222 Rem for a 10" Contender. I'm glad I had a tall stack of sandbags, otherwise I'd have scorched the hood of my Dad's Trailduster - 10" is a bit short for the .222 round to fully burn the powder charge!)

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  2. I have the Type 30 that shoots 6.5x50 Japanese.

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  3. Very nice, and a good alternative to the high $$ stuff!

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  4. Happy Thanksgiving to you and Audie Murphy

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  5. Wow! I'm just catching up on blogs and read this one - very cool!

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  6. This post is really too informative to us, good perception of images and good description by which any one can get information what they want to this post.......As for as my thinking is concerned this one is the best post.

    Thanks for sharing such a informative post.
    30-06 ammo

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  7. Where can I get a MK I eyeball caliper? Seriously thaks for the information. I just picked up a 7.7 at a yard sale and want to try it out before I send it off to be re-barreled to a more available caliber. Thanks tons.

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  8. Gotta remember that Dremel tool; much better than working it all off with the manual trimmer.

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  9. Thanks for the great posting. Was curious as to what you considered a light load for the inherited Arisaka 99 that your friend acquired. I have one also ("substitute standard"/Kokura Arsenal) and has not been fired since around the same time. Just cleaned and ready to test fire.

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    1. The light loads were done up with Win748 and pull-down .311 bullets from 7.62x54mm ammo. They were also failures at the range. But don't worry about the loads. The Arisaka is one of the strongest actions out there, which is why so many get re-chambered as belted magnum receivers. Follow the recipe above and you won't even come close to over-loading the rifle. These Arisakas are tough. Real tough.

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