How accurate are Japanese rifles?

[rayg]

I suggest not judging Arisaka accuracy on the basis of lead bullets, which do not take well to Metford rifling.

Jim

Exactly! I only mentioned that they are even worst with cast bullets then with my other reloads. And that I can't get cast bullets to shoot well in the Japanese rifles. Ray

[Bruce McAskill]

Most surplus military rifles I have shot with Norma ammo did not shoot it well at all except for one type 99 that was like new that would fire a one inch group with it at 100 yards. The Carcano will not shoot well at all with any standard 6.5mm bullet with a .264 diameter. The rifling in them is a gain twist that uses a bullet of .268 diameter. Hornady now makes the correct diameter bullet for reloading of the 6.5 Carcano and accuracy is much improved. I do have a type 38 rifle that no matter what I shoot in it is not accurate at all. Yet a type 38 carbine I have can and does shoot two inch groups at 200 yards with the right load. If your going to try lead in these rifles then the first thing to do is to slug the bore as there is a great variation in bore diameters with them. Use a lead bullet as close as possible to your bores diameter and it should shoot well.

[rayg]

Bruce I miked all the bores and I make the cast bullets .002-.004 larger then the grove dia. Doesn't help so far but will keep trying as it has become a challenge for me to find a right bullet and load in cast for them, Ray

[avlane]

I have two type 99's with nice looking bores. I like the sights and experimented with quite a few different loads. my best results were with IMR 4320 and 150 grain bullets (Hornady .312). The load came from the Sierra manual. Results were OK, but I could not get these rifles to shoot even close to the consistency of some other milsurps, ie, K31, Sedes, 1903/03A3, Krags, etc.

As to the Carcano. I have a 91/41 with a very good looking bore. Forget .264 bullets unless six inch groups are satisfying. I tried Hornady .268's. Group size was cut in half, but I experienced pierced primers, blow back, etc, and decided maybe this one is a little questionable safety wise.

[Patrick Chadwick]

Avlane, I fired off all the factory ammo I had, just to get fire-formed cases, and then reloaded with the 0.268 Hornady seated out about as far as the original Carcano rounds were (OAL 75,25 mm, in my 91/41), to get the bullet as close up to the throat as reasonably possible. 1-1/2" groups at 100 meters with 28-30 gn of Reloder 15. No signs of overpressure. And don't forget the standard reloading tip for milsurps with chambers of uncertain dimensions - neck sizing only, using cases that have been fire-formed in the same rifle!

BTW, take a look at the tip of your firing pin under a watchmaker's eyeglass. It may be a trifle jagged. Not good for primers.

As to Arisaka: apparently (I do not have one) they have a Metford-style polygonal rifling, which has led to people thinking that the rifles were shot-out because they could not see any sharp edges! As a non-Arisaka expert, but a fairly experienced black powder shooter, I can tell you that polygonal bores are very sensitive to the size of bullet and its hardness.

Can you get hard lead bullets in varying diameters? Over here, for instance, there is a company called Rifle Bullet Caster GmbH & Co (Riflebulletcaster GmbH & Co.KG.) who make lead bullets with a Brinell hardness BHN 22 and diameters of 0.268/0.270/0.272" (weights 126/128/130 gn) for the Carcano and Arisaka rifles. Likewise 0.314/0.316/0.318" (weights 177/178/179 gn)for the 303 and 7.7 mm Arisaka. Worth trying befre you give up or start experimenting with expensive molds!

Patrick

[rayg]

Patrick, I've been water dropping my cast bullets that I've used in the 7.7 Japanese rifle and they come out approx BHN 22 Brinell hardness. I think I will next try softer, non water dropped, bullets in the area of BHN 10-12. Maybe the softer bullets will work better in the Metford-style riling. Maybe, maybe not, but will try that next. Ray

[Patrick Chadwick]

It could well work with somewhat softer bullets, but BHN 10 is going right down. It's about what I use for my BPCR rifles, so you may find BHN 15 better. Unfortunately, the whole matter is a trade off between softer bullets - which will obturate well to fit the bore, but will strip off in the rifling if you drive them too hard (which I think is one reason behind the Metford polygonal rifling, the other being reduced fouling (???)) and harder bullets - which must be a closer fit, because they do not obturate so lightly, but can be driven harder without stripping.

Patrick

[rayg]

I use light loads with all my cast bullets between 1500-1700 fps. even with softer bullets that should'nt strip off lead hopefully.
My favorite and most accurate loads for my 303 and 30-06rifles is only 10 grs Unique or 16 grs 2400. Light but accurate.
I tried these loads with the 7.7 with the hard bullets and did'nt get good groups. Maybe the softer bullets will work better, Ray

[Bruce McAskill]

Ray you said you slugged your bores and your bullets are .002 to .004 over bore size? If so you might want to try going just .001 over bore size and try that for accuracy.

[Patrick Chadwick]

If the Arisaka does indeed use a Metford profile, then the following info for the Lee-Metford 303 may be applicable.

Please not that my conclusions ONLY apply to lead bullets that can obturate sufficiently to fit the rifling profile. It does NOT apply to jacketed bullets.

A drawing of the Metford profile is shown on P10 of "British Service Rifles and Carbines 1888-1900" by Alan Petrillo. For those who do not have access to this drawing, I can only describe it as a seven-sided rounded-off polygon. No sharp edges at all. Anyone who has one of the English 7-sided 50 pence coins has the right profile in front of him. When these coins were introduced there was no little astonishment. How would they function in coin slot machines? The answer is: quite OK, thank you, because the profile is made to have a constant diameter, although it is circular, i.e. NOT a constant radius. In other words, it rolls OK through a slot machine.

The point of this little diversion via coinage is that, although he is no longer around to answer the question, I think that Metford's thinking was precisely the same. The lead bullet should not be cut, but deformed to fit the rifling in a way that spreads the deformation equally around the bullet.

Following this concept, the correct diameter for a bullet to fit Metford rifling is NOT the diameter of the circular plug that will just pass through the bore (what you might think of as the "lands" or "bore" diameter". NEITHER is it the diameter given by the "lands" + 2 x depth of rifling (what you might think of as the "groove" depth). Instead it is the bore diameter + 1 x depth of rifling.
I the case of the Lee-Metford 303 this would be 0.303" + 0.0045".

In other words, the ideal size would be 0.3085" for a perfect Metford bore. A bullet that is slightly smaller will obturate to fit the bore. A bullet that is too large will result in higher pressure that a "perfect match", whatever that may be.

By the way, the constant diameter nature of the Metford profile means that if you slug the bore, it doesn't matter where you measure the slug diameter, it will always be the same (to the level of accuracy needed in practice). In fact the Metford profile does deviate a tiny amount from the constant diameter, having very narrow lands (0.023"), which would make the fit a gnat's whisker tighter. On the other hand, a real rifle is hardly likely to have a mint bore after all this time. So 1-2 thou larger may be better.

So my best starting approximation for an Arisaka is: Slug the bore, measure the slug diameter, get lead bullets with BHN 13-6 and BHN 20-22 in the exact measured size, rounded up to a full thou, also that plus 2 thou (i.e. 4 versions, if you can get them or cast them), load very moderately for a muzzle velocity in the range 1500-1800 fps and try it out. If you load too heavily for the lead hardness you will probably see it as lousy grouping and keyholing. I think you will find that BHN 13-16 is quite size-tolerant, but load sensitive, whereas BHN 20-22 will be less load-sensitive, but more size-sensitive.

Patrick