Arisaka Rifling Question

G

GunAddict1962

Inactive
I recently slugged the barrel of my T99 Arisaka. The bore is brite, of course, as it should be with chrome, and the rifiling is visible. However, when I inspected and mic'd the slug, the land and groove impressions were barely visible. It's difficult to estimate how much the rifle was shot and cleaned back in the day using a steel cleaning rod. The rifle is complete, all original, and in very good condition overall. My question: Back in the day, were the lands and grooves in T99s "standard" or were they "micro," for a lack of better description? Did the Japs figure that since the bores were chromed, the lands and grooves didn't to be the standard depth/height? Or did they lose some of that in the chroming process? Maybe I just have a heavily shot/cleaned/worn bore. Woudn't guess that from the condition of the rest of the rifle. BTW, at 50 yards it's a great shooter for iron sights and my old eyes, and that is shooting .310 bullets out of a bore that slugged at .312.

Thanks
 
I have never heard of a Arisaka with a chromed bore. Rifling in bores is never very deep, usually .004", shallower in smaller bores. You say your slug miked .312", that would be basically brand new.
 
Chroming on T99s was standard. Japs were ahead of their time on that. A response to the tropical climate and corrosive ammo. Difficult to measure accurately but the land a groove marks on the slug are almost inperceptible. Recently slugged my old Enfield, Mauser, and M-Naggant. No problem reading the slug from any of them. Clearly visible land a groove marks, even enough to feel with a finger nail if you're careful. Not the case with the Arisaka. Need a magnifying glass to see the very slight marks on the slug. If you say 004" would be a standard measurement, then these would be like .001" or .0005", yet they still effectively stabilize the bullets which punch nice round holes in paper at 50 yards.
 
Looking down the bore of an Arisaka one would think it was shot out. Not so. That's the way they made them.
Maybe the chrome plating has something to do with it. But they shot plenty accurate.
 
Most of the type 99s do in fact have chrome bores. However, there are some that do not have chrome bores. I know because I have an example and it is a great shooter and slugged out at 312.
I have examined a few that had the chrome bore shot/corroded out. I once had one that could not hit a 36"x36" target @ 25 yards. If it did, it was a keyhole.
 
That type of rifling has nothing to do with the chrome plating, which was standard on the Type 99 right up to the very late rifles.

The Japanese used Metford rifling, something they got from the British, who were using it in the Lee-Metford (Lee rifle, Metford rifling - Lee Enfield is Lee rifle, Enfield type rifling) at the time the Japanese were designing the Arisaka rifles and they never saw any reason to change it.

Metford riflling was designed to minimize cupro-nickel fouling. Lands are rounded off and looking down the barrel the rifling appears as shadows rather than the sharp appearance of conventional rifling.

If one is a bit unscrupulous, and one wants to buy a Japanese rifle, one can get a lower price by telling the owner that the rifling is all worn out.

Jim
 
Thanks, Jim K. That's very informative and helps to explain it. Rounded lands would definitely make the marks on the slug less visible.
 
JamesK is right, the tooling on Arisaka's is different. Shot out chrome bore? The chrome is only a couple tenths thick and I have never seen that. You may have had a late war model. I don't remember when the change over happened, but they did go to an inferior grade of steel in the barrels late in the war. I am thinking late 1943?
 
Just FYI, the Type 38 (and previous models) did not have chrome bores; only the Type 99 did. I expect they dropped the use of chrome when supplies of the metal ran out and new supplies became unobtainable. (AFAIK, neither Japan nor the nearby mainland has any chromite deposits; Japan normally obtained chromium from India, but that would have been impossible during the war.)

Jim
 
From the stamp on my T99, I think it has something that appears to indicate Series 23. I don't think that was late in the war. Anyway, the rifle is very accurate at the only range at which I've fired it: 40-50 yards. I suspect with fresh eyes or modern optics it could hold a few inches at 100 yards. Not at all bad considering the circumstances. Seriously, more accurate than my WWII era Mauser, Enfield, Mossin N, & M1 Carbine--all in fine condition. Would have never thought so about an Arisaka until I acquired this one and shot it. Have been shooting for about 40 years, was a distinguished rifle expert and sniper in the military. The Japs had a few things very right back in the day.
 
The myth that "Jap rifles are no good" is right up there with other American morale-building stories from WWII. It didn't matter about the rifles, everyone knew that "Japs can't aim right because they have slanty eyes" and "Jap airplanes are made of tinfoil". Sure.

Jim
 
Speaking of wartime stereotypes, i heard a Marine who was on Saipan, I think, say he wore his helmet on the right side because bullets dont come from the left, "Ever see a left handed Jap?"
 
I sometimes have to remind myself to be careful to judge military weapons based on the purpose for which they were built and the resources that were available at the time. A properly trained soldier with a dependable bolt gun made a lot of sense when ammo was short, resupply was seldom, and war was filthy.
 
I have no doubt that Japan would have supplied its army with semi-automatics had it been able to do so. Semi-auto rifles don't just fire faster, they significantly increase the hit ratio, so ammo usage balances out. Certainly the trend was there and Japan was well aware of it, even making a few copies of the U.S. M1 rifle in 7.7.

Jim
 
And even a copy of the Pedersen, but with a rotary magazine instead of the enbloc clip that Mr P sold hard enough that they pushed it on Garand.
 
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