6,5mm Japanese Arisaka Ammuntion Dimensional Revelations (Photo Heavy)

[jmoore]

Some details and photos of the cases after firing- see the link: Japanese Ammuntion and Rifle Testing for the range report (posts #1 and 2). This post will then make more sense!


#21a


#21b Yup, two pierced primers- that and the misfire halted further testing of this ancient ammunition!

The Milsurp rounds above- note the odd crimp on the misfired example- Some more were found mixed in on other chargers pulled from boxes w/loose lids. Repackaged?


#21c The raised crimp made bolt turndown an exercise. Note the shiney areas polished and "mashed" more flush during bolt closure.The angled locking faces found on many Type 38s were of great assistance here!


#21d Primer back-out w/ the use of o-rings was reduced to 0.000" to 0.003" on the Series 27 rifle whilst using Hornady ammo. Most were flush.


#21e The Type 97 had a little more primer back-out, but not much more. Few altogether flush.


#21f


#21g The Norma (packaged as Federal/American Eagle) primers backed out anywhere from 0.000" to 0.007". Still, the o-rings were an improvement over previous sessions.


#21h Cases bulged, both milsurp and commercial, but no signs of case head separation were seen.

[Patrick Chadwick]

-ring trick works, but isn't nearly as effective on the semi-rim as with rimmed cartridges.

I just tried loading a cartridge with an O-ring, without actually firing it. The extractor cut clean through the O-ring. So this method would be heavy on O-ring consumption in my rifle. Did you remove the extractor for your experiments? Obviously I could do that, but it would mean using a brass rod to push out each fired case. Any suggestions?

Patrick

[Parashooter]

I suspect you're spinning wheels with the O-rings. Take a look at your Arisaka's breech. If it's like the one in the picture here, you'll see there just isn't much contact area for something as squishy as neoprene to make a consistent difference in potential case stretch.


This is a very different breech arrangement than the full circumference contact we see on a Lee-Enfield

Frankly, even with the thinnest rims reported, you're not going to get horrific stretch the first time you fire your cases. For subsequent uses, adjust your sizer for zero end-play to allow the case to stop on the shoulder instead of the rim - just as you would with a rimless cartridge. If the potential for a little stretch on initial firing really bothers you, put a light film of castor oil on the cases before firing. Use a load about 15% below normal if you're worried about increased bolt thrust (which wouldn't concern me a bit in the very strong Arisaka action).

[jmoore]

I just tried loading a cartridge with an O-ring, without actually firing it. The extractor cut clean through the O-ring. So this method would be heavy on O-ring consumption in my rifle. Did you remove the extractor for your experiments? Obviously I could do that, but it would mean using a brass rod to push out each fired case. Any suggestions? Patrick

No mods to the extractor in either rifle, but I did end up just dropping them in the chamber and let the extractor hop over the puny rim. Not a practice that I would do with any Mauser 98 derivative, but didn't take hardly any extra force here.

As the primer protrusion was noticably reduced from previous sessions, it works at least somewhat.

I reckon the rings DO loose some effectiveness due to the barrel face cuts, but I ran them on the "fat" side. (Nice photo of the breech opening, Parashooter!)

Stupidly enough, I think running the charge weights higher would help form the cases properly. Primer set-back always seems the worst when loads run light. I first noticed that phenomenon when loading for an M1917 back in the early '80s. (.30-'06, obviously)

Too many dramas recently to do more in this area. Maybe soon.

[ireload2]

To get rid of the extruded primers just jack up the pressure. It also helps to have a nice polished chamber and lubricated brass.
For a different take on this round the Type I Carcano barrel has no feature that will touch the front face of the rim. It is strictly head space on the shoulder.
Probably the best brass to use is .303 brass cut down but it takes a lot of work.
The chamber cast of one of my rifles a T38 has a .264 on the button groove diameter.

[jmoore]

To get rid of the extruded primers just jack up the pressure.

Stupidly enough, I think running the charge weights higher would help form the cases properly. Primer set-back always seems the worst when loads run light.

I believe we're on the same page here.

The chamber cast of one of my rifles a T38 has a .264 on the button groove diameter.

I wonder why the military bullets run small? The bores don't seem to be taper cut or anything odd. (aside from the complex rifling geometry, that is! It keeps reminding me of the early Glock rifling.).

[Bruce McAskill]

If I remember right the T38 uses A type of Medford rifling which is like the polygonal rifling like Glock uses. Not a good choice for lead bullets and I have tried but with the right rifle the 139/140 weight bullet can be accurate. I do have a carbine that using 30 + grs. of IMR 3031 and a Hornady 140 bullet (It doesn't like Sierra bullets.) I was able to get a two inch five shot group at 200 yards. I was also using 35 Remington brass at the time and it all worked great. I don't know if I can do it again as my eyes were a lot shaper back then but I still have the carbine.

[centex bill]

Has anyone built a modern rifle in 6.5 Japanese round using todays actions and barrels?

What has been the results? Can the cartridge be loaded to higher velocitys if fired in a modern custom built rifle?

Thanks,

Bill

[andiarisaka]

Bill, I had a fellow write me once, said he'd gotten a 6.5mm barrel for his contender chambered in 6.5 Jap. Back about the time of 9/11, I wrote Norma complaining about the ill fitting brass. I also told them that I had been making up ammo based on the 303 British headsize. Wasn't long after, the Norma website showed their 6.5 Japanese with the .303's headsize and the .303's .059 rim. 6,5 Japanese Arisaka - Norma
Others have looked for said ammo, but nobody has said they found it yet. They probably had tons of that old brass they've not yet sold! The old Norma cases began to separate upon the second firing, even though I neck sized them only before reloading. Now, I either swage down .308, or use .303 British or 30/40 to feed my Arisakas, with .303 being easier to come by. I even took out an ad in the American Rifleman selling my swaged down GI .308 around that same time. Glad I didn't get many orders, cause it was real labor intensive, and boring! I can't help but wonder how many rifles were thrown away by folks who thought they had a headspace problem, when the real problem was the thin rim and small head of the Norma cases? Incidentally, the type I Japanese rifle has a tighter chamber than the Type 38.

[riceone]

I've been sorting through my amm in the last day or so and I found 40 or so rounds of 6.5x50 ammo that was loaded in cases made from 7.62 x 51 Nato brass. When I made this brass I used a swadge die (that I made) and recuced the base of the case down to .456" (if my memory is right) and then run the cases through and old Herter full lenth die doing it in steps till the bolt closed on the case with no resistance. This produced a case that did not swell at the base and it fit the chamber so there was no stretching later. This is the only way I know to have a case that fits the chamber as it should. I was making and selling the swadge die and I think there is someone on this board that has a copy. With the variance in Japanese chambers you are going to have to fit each rifle seperately IF you want a perfect fit.