Is the 7.7 Arisaka cartridge inferior to the .308

[BJung]

Why is the 7.7 x 58 Arisaka cartridge inferior to the .308? One article I read ranked the 7.7 Arisaka as equal to the 30-40Krag. Another compared it to a .303 British.

The casing dimensions of the 7.7 is slightly larger than an 8mm Mauser. I'd say it's a necked down 8mm Mauser casing. This should give it better performance than the .303 British which uses the same bullet caliber.

The 7.7 casing is slightly larger than the 7.65 Belgian Mauser, Argentine Mauser, Peruvian Mauser, and Turkish Mauser cartridge. I read an article that ranks the 7.65 Belgian between a .308 and a 30-06. It too shoots the same caliber bullet.

The .308 is rated as superior to the 7.7 Arisaka. One has a .308 caliber vs a .311. Not that much of a difference.

In reality, I've started testing loads for my 7.7 Arisaka. My most accurate loads seem to be the same as those published by Ken Waters'. This load will print group with a POI at 100 yards using 100 meter settings. This means that I could continue loading up so and find a node at a higher POI. I just didn't because my primers started to flatten.

Is there an American/Western bias to the .308 then to the 7.76 Mauser or is there a reasonable explanation? Please cite your source if you can.

[ligonierbill]

It's not far behind the 308, if you check Hornady. They load their 150 spire point to 2,800 fps in 308 and a similar 150 to 2,700 in 7.7x58. A little skewed, because their Arisaka test rifle had a longer barrel. The 99 is a strong action, if it is in good condition. I could not find a SAAMI spec, but CIP MAP for 308 is 4,150 bar vs. 3,100 bar for the Arisaka. That will limit its performance. Don't know what pressure Hornady used.

[Bart B.]

The 7.7 Arisaka originally had about 41,000 psi max average pressure spec; as I remember. 308 Winchester has 62,000 psi MAP spec

I've read many made in 1944 or later often had poor heat treatment for receivers.

[44 AMP]

Is there an American/Western bias to the .308 then to the 7.7 Arisaka or is there a reasonable explanation? Please cite your source if you can.

is there a bias? yes, and its "We won!"

Seriously though, don't confuse the possibility of potential with the actual round as loaded and used,

The 7.7mm Arisaka IS the .303 British in a slightly differently proportioned rimmless case. Performance of both rounds as used in WWII is approximately identical. A 180gr (ish) bullet at approx. 2400fps

During the pre-WWII era the Japanese were heavily influenced by Great Britain. They drive on the same side of the road as the British. The Imperial Japanese Navy was extensively patterned on the Royal Navy model, heck, 2 of the WWII Japanese battleships (sunk by the US in the Solomons) were made in Great Britain.

So, when the Japanese were looking to replace their 6.5mm they chose the performance of the .303 British round, and put it in a rimless case for ease of use in automatic weapons. The same bullet size, velocity and pressures just a different case.

Is the 7.7 Jap inferior to the .308 Win?
Yes, as loaded and used. Lower velocity, lower pressure = inferior. Not by a lot, and not by any amount any animal can tell but it is a lesser round.

The larger 7.7 CASE allows for the potential of exceeding .308 Win performance, but only when used in a strong enough rifle and loaded to much higher pressure than the military loading. The 7.7mm was a 40K psi round, the .308 is a 50K+ psi round and that's using the old measurement systems.

A lot has been made about PO Ackley's blow up tests where the Arisaka action turned out to be "the strongest", but other than as information, the "strength" of the Arisaka is meaningless. In good condition (and not one of the famous "last ditch" rifles, the Arisaka action is strong enough to handle .308 pressures, but other than handloaders, it has never been loaded to those levels.

Additional factors that worked against the 7.7 Jap in the US are Arisaka rifles were not well liked, and were not as well suited to conversion to sporters as Mausers. (it can be done, and done well, it just took more work)

Arisaka ammunition was never imported into the US in large quantities, Japanese military stockpiles were either destroyed or remained in Japan, unlike European WWII surplus rifles and their ammo, which were widely sold in the US until the stock ran low.

There have been NO sporting rifles commercially made for the 7.7. Everyone you'll find is a converted Japanese milsurp. (*there might be a custom rifle here and there, people do weird stuff )

Essentially, 7.7mm Jap production ended with the fall of Japan in 1945.

And, generally when authors are rating rounds based on their performance levels they are doing it based on what the rounds in use ARE, not what they can be.

There is a parallel with the .308 win and the .30-06. The military load for both of then is virtually identical. Same bullet same approximate speed. (pressure are different)

In commercial loading, sporting manufacturers have taken advantage of the larger 06 case to increase performance over the .308 Win.

No such thing happened with the 7.7mm Jap. There was no market, so no profit in doing it.

Your Arisaka was built to shoot in the 24-2500fps range with 180s, and slower with heavier (215gr) bullets. Run it there, and all should be well. You CAN upload it some, but why??

when you start getting flattened primers, STOP!!! Doesn't matter what velocity you are at, or what ANY book says you should be able to go to.

Listen to your rifle, the one in your hands, NOT the books. When your load flattens primers your rifle is telling you to stop, that particular combination of rifle and ammo components is reaching the upper limit of safe working pressure. If you're at, or close to where the book says max, fine. If you're below that, stop anyway. Listen to the rifle, not the book which used a different rifle.

[Bart B.]

44Amp says there is a parallel with the .308 win and the .30-06. The military load for both of then is virtually identical. Same bullet same approximate speed. (pressure are different).

Is a 2000 psi pressure difference and 100 fps velocity difference a big deal? No.

But the difference between a 1:10 and 1:12 rifling twist made one more accurate.

[Bart B.]

44AMP,

You say the 308 is a 50K+ psi round and that's using the old measurement systems erroneous terminology. It's a 52K cup system today using virtually the same system. Both military and commercial pressure systems in the 1950's used crushed copper units of pressure then erroneously dubbed them as pounds per square inch. SAAMI lists both system's pressures now. 62,000 psi and 52,000 cup.

[BJung]

I have not read about the .308 in comparison to the 30-06. I suppose changed the powder to increase the pressure.

Unfortunately, I do not have a .303 case to compare it's volume/weight to a 7.7 Arisaka. I still think the 7.7 Arisaka case is larger and maybe someone can compare the weight of similar powder or water that would fill their .303 to my 7.7 Arisaka case.

So, how is it that the 7.65 Belgian Mauser case is smaller but the MV test is higher per powder charge? Is there something in the design of the case? Why is pressure lower in the 7.7 to the .308? Let's say I take three identical test rifles, one chambered for .308, 30-06, and 7.7x58 and load them up to the maximum node. The 7.7 should be in-between the 30-06 based on the case size.

This is like the 30-40Krag compared to the .303 British. To me, the 30-40 Krag in between the 30/30 and the .303 British.by looking at the outside case dimensions. If so, then that's like saying the 30-40Krag is like the 7.7 Arisaka. There's an obvious different in case size here.

Also mentioning is rifling. The .308 is a 1:10 twist, yes? So, a faster twist should mean a lighter bullet. But, the Arisaka has a 1:9-3/4" twist and prefers the heavier 175 gr than 150gr bullets. Please explain?

[Bart B.]

Standard 308 Winchester twist is 1:12. Same for 7.62 NATO. A good compromise.

Heavy bullets need faster twist; 1:8 for 240 grain bullets. Lighter bullets, slower twist; 1:13 for 150 grain is best.

[Unclenick]

QuickLOAD lists the 303 British cases as having 56 grains of water overflow capacity, same as it gives for 308 Win. It lists the 7.7 as having 61 grains of water overflow capacity. The 30-06 it lists with 68 grains of water overflow capacity. I find the program typically is a grain or so short of what you measure—just not always. Nonetheless, that gives you some idea of the relative differences.

Working up loads of H4895 in QuickLOAD, the .308 Win comes out with about 7% higher velocity (about 200 fps) and 15% more muzzle energy with 150-grain bullets in both. The amount of powder is 2.6% lower to reach the 7.7's CIP pressure, despite the greater case capacity.

[44 AMP]

So, how is it that the 7.65 Belgian Mauser case is smaller but the MV test is higher per powder charge?

How is it? Well, without knowing all the needed information about the MV test you are referring to, who can say??

Different rifles yield DIFFERENT results, and identical seeming rifles can yield different results. Things are not linear or perfectly consistent. Many factors affect the outcome, some obvious, some not so much.

A quick look in an old LYman book shows me the Krag, the Brit, the Jap, and the Argentine/belgian powder charges vary about 2-4gr with the 180 bullet. Velocities varied a bit but were within a 100-150fps or so range of each other.

Except for the Argentine, which was faster. HOWEVER, I doubt the Argentine was faster because of anything to do with the case design or capacity as much as it did with barrel length. Because the rifles they used had 22" for the Krag, 25" for the Brit and the Jap, and 29" for the Argentine.

SO, without knowing details like that, no MV test report is worth anything.

Also, were you to build "identical" barrel rifles in all those different calibers, you'd most likely get similar, but not identical results, and since you're handloading "to the node" whatever the hell that means, those results would likely be different than the performance of those rounds in their respective service rifles.

Never forget that the performance specs of different rounds are determined by their original makers, for the rifles they were originally chambered in. UI had a Ruger N0.3 in .30-40 Krag. Had I felt like it, in THAT rifle I could have loaded the .30-40 to much higher pressures and speed than the factory load. However, that ammo would not have been safe to shoot in a Krag rifle.

Same thing for the .45-70 from a Ruger vs a Trapdoor Springfield. It is the RIFLE that determines the limits, first, and cartridges are made to us in specific rifles (at first). Sometimes they never get used in anything but the original rifles, sometimes they find appeal across a broader range of designs.

[Geezerbiker]

I started reloading for the 7.7x58 in the late 1970's at that time all the books listed the loads way on the light side. I worked up to using .308 Win loading data and I was very satisfied with the results. Years later I bought a new Hornady loading manual and they listed hotter loads than I was using.

Personally, I'm happy with the lighter loads I was making and I'll not likely ever load them hotter for it. I also have many more rifles now so the my old Arisakas don't get the attention they used to.

On a side note, I found that my load made with reformed .30-06 military brass was more accurate than the loads using Norma 7.7x58 cases. I think it's because the thicker neck holds the bullet more centered in a sloppy military chamber. Well that's my story and I'm sticking to it...

Tony

[Bart B.]

Originally Posted by burbank_jung

I have not read about the .308 in comparison to the 30-06. I suppose changed the powder to increase the pressure.

In 1970, after the 308 cartridge had broken all the match records held by the 30-06, i called Winchester to get some facts about its development.

Frankfort arsenal bought 300 Savage cases from them to develop their new cartridge. While accuracy was better than the 30-06, velocities were more than 100 fps slower; the case had to be longer to hold more powder and keep maximum pressures at 50,000 cup for velocity needed.

The arsenal ended up using a longer case and sent some 7.62 NATO ammo to Winchester. It tested 50,000 cup on the military pressure system, but 52,000 cup on Winchester's commercial cup system.

Years later, when piezoelectric pressure systems were used, reference ammo measured 62,000 psi. It measured 52,000 cup on the old system.

I'll post a link to SAAMI's document listing all sorts of technical stuff.

https://saami.org/technical-informat...mber-drawings/

Here's another good document.....

https://www.docdroid.net/shd8/the-tr...d-762-nato-pdf

I'm the "well known high power match competitor" the author mentions.

[Unclenick]

Here's a SAAMI link. Incidentally, PhilFAL posted that article on this board first, as far as I know. The copy hosted here at then of this link.