Various threads claim that the 7.7 Arisaka is a rimless version of the .303 Enfield. The load data is close. Has anyone read any threads of shooters transferring the primer, powder, and bullet directly to an Arisaka 7.7 case and shooting it?
Various threads claim that the 7.7 Arisaka is a rimless version of the .303 Enfield. The load data is close. Has anyone read any threads of shooters transferring the primer, powder, and bullet directly to an Arisaka 7.7 case and shooting it?
Sound feasible as long as you ensure the loads are safe. Check bullet diameter., load, etc first. Others will be along to discuss further.
Keep in mind there were three different 7,7 rounds and make sure you are reloading the correct one correctly.
Why not just shoot the 303 in a LE and dispose of them that way?
There were THREE "7.7" Japanese rounds.
7.7 x 56R is IDENTICAL to .303 Brit. It was, like the entire Japanese navy, based on Royal Navy practice. This extended to "traditions" (delete rum, insert Sake) and uniforms.
The Japanese ARMY was modeled on PRUSSIAN practice and doctrine, with a big chunk of Bushido thrown in
The army (and, by extension, the Air Force) did things their own way. There is a 7.7. "semi-rimmed" round, basically a semi-rimmed, "improved" .303, developed originally for machine-gun use, and a 7.7 RIMLESS, basically the semi-rimmed MG round with a less prominent "rim", for rifle use.
What were they thinking? Especially as the 6.5 x 50 was still ubiquitous.
Because the "initial" 7.7 x 56R was a straight copy of the .303, it used a .312" bullet. In a rare bit of logical thinking, the later two Japanese 7.7mm rounds used the same bullet diameter.
The same "Mk Vll" .303 bullets work well in 7.65 Argentine and variations on that theme, AND 7.62 x 54R, if you feel a desperate need to waste valuable .303 Mk Vll bullets in a Mosin Nagant or DP, etc.
For the truly obsessive, Russian 7.62, be it x 54, x 39 or x 25, is REALLY, "7.62"mm BORE diameter, exactly the same as the .30-06 AND 7.62 NATO, share a .300" nominal BORE diameter. The difference is the nominal GROOVE diameter, 9plus or minus engineering / manufacturing tolerances.
Note that those crafty Finns developed their own variation for their TKIV sniper rifle series; the 7.62 x 53R. This is EXACTLY the same basic cartridge as per the parent 7.62 x 54R, BUT topped off with a .308" diameter Sierra Match King and fired through barrels optimized for the x 53R loadings
KNOW YOUR AMMO SPECS!
What's a few thou among friends? See also: "Close enough for Government work".
Another internet myth . The 7.7x58mm rifle cartridge has nothing to do with the .303 Brit other than using the same bullet dia . It is not a rimless version as it has a different case shape and volume . It IS 7.7mm version of the 8x57mm cartridge . They had been fighting the Chinese who where using the 8mm , they wanted that performance gain over their 6.5mm . They just necked down a 8x57mm case to take a 7.7mm bullet they already were making and so they did not need to retool to make 8mm barrels on top of 7.7mm . A 8x57 case necked down gets a little longer , hence the 58mm case length . A 7.7 case can be made from a 8mm case [ not a 303 brit ] and any 8x57mm load data is fine for the 7.7mm as they are the same except for a .012 in bullet dia .
https://www.milsurps.com/attachment....38&cid=1&stc=1
Be cautious if forming 7.7 Arisaka cases from 8x57 Mauser. There are significant dimensional differences, notably the head-shoulder (headspace) length.
Furthermore, a LOT of Type 99 rifle chambers are "generous", to say the least. Apparently hand-loading was not big in the Imperial Japanese Army.
There are occasional lot of Norma or Privi Partizan 7.7 loaded ammo and / or unfired cases briefly in the shops. Specialty reloading suppliers would be a good place to start.There are also a couple of European sporting cartridges that have a similar diameter at the rear. If you can rustle up a hundred or so cases, that will keep you grinning for decades, unless you keep losing them whilst deer-hunting or similar.
Whichever way you go, neck-size with minimal "shoulder bump If you also neck anneal every-do-often, the cases will last a LONG time. It can all get a bit fiddly, but that's the additional price for playing with "exotic" goodies.
Compare the dimensions of the Mauser cartridges with many many other cartridges and you will find a common head and rim size, including the 45ACP. The same with many big game cartridges.
The 8x57mm case head size was developed by the German military and Mauser starting with the 8x57 and 7.65x54 and 7x57 . They wanted to be able to make the same rifle and case parts and tooling and not have to change anything but the barrel . The US worked off of those to make the 30/03 - 30/06 , which was used as the base for most US cartridges , just like Mauser used it as the base for all Mauser cartridges . That is why the 7.7mm is made from the 8x57mm . All other countries used a different case head , Italy , Sweden , Japan with it's 6.5mm , the Swiss , England , France , Russia , Austria and so on .
Attachment 121377
Imperial Metric
A .473 12.01
B .472 11.99
C 23 deg
D .430 10.92
E .338 8.58
F 1.870 47.5
G .413 10.49
H 2.283 58
Nominal case dimensions.
Figures from various reloading manuals vary by a 'thou or two, here and there.
I'm guessing that the original arsenals were probably not handing out technical data to reloaders at the time this cartridge was in active service.
Here's CIP dimensions for 8x57 - and SAAMI, too -
https://www.milsurps.com/attachment....84&cid=1&stc=1 https://www.milsurps.com/attachment....83&cid=1&stc=1
My opinion is that the 7.7 Arisaka is loosely based on the 8x57 Mauser case, but was finalized a tad fatter at the back end and longer body-to-shoulder. The fat rear isn't a problem when forming 7.7 cases from 8mm or .30/06 as long as excess pressure is avoided (see image below), but .040 to .050 excess headspace could be one when forming from 8x57 without precautions.
https://www.milsurps.com/attachment....85&cid=1&stc=1 https://www.milsurps.com/attachment....86&cid=1&stc=1
My original Japanese WWII 7.7mm ammo has a .470 head size .
I have never used .303 to make any other caliber (a bit too pricy for me to be doing that), but I have used pulled 7.62x54r to make 7.7 Japanese. Had to develop my own loads starting low and slowly getting higher. I would also only use the load data I made for that particular batch of ammo as there is so much different 7.62x54r about.