Uhhhh... not really. These substitute standard guns had to pass proof just like their predecessors. "Last ditch" isn't really the proper term, but everybody uses it. The best way to tell if a 99 is safe to shoot or not,, is to look at the upper tang. If it is detachable, you are good to go. If it is one piece with the receiver, it is a cast, un-heat treated receiver. Do not shoot!Metallurgy was suspect on the final guns....I wouldn't shoot it.
Frank DeHaas, in his classic, "Bolt action Rifles" has a section on how he tried to blow up a type 99. He chose a "last ditch" specimen that was so ugly he originally thought it might be a training rifle. He rechambered it to 30-06 and used 180 gr. bullets. He started out with a case full of 3031. This was an overload. Nothing happened, beyond flattened primers. Next was a case full of 4198, with the same result. A case full of 2400 finally did the trick. After all was said and done, there was no setback to the lugs in the receiver, which was intact and still serviceable!! That last load probably generated in excess of 100,000 PSI. Granted, this was not a true scientific study. Only one test subject was tested. He might have tried this with a second rifle and blew it up with the first load, but....Good find! As most know, there aren't many bolt-action rifles that are "stronger" than an Arisaka.
The 99s bolt, conversely, has locking lugs slightly SMALLER than the Mauser's and the left lug IS slotted for the ejector. The legendary strength of these actions has to come down to the steel alloy used in their construction and the heat treating. I find it hard to believe the Japanese knew some magical trick that they learned from space aliens. I wonder what their secret was??
A logical conclusion. (Fixed it for you.)I assume that the centuries of sword making provided some experience?
If the chamber is anywhere near spec on the 99, it is literally impossible to chamber an 06 round. One look at the pic will show this. I think this rumor got started during the Korean war, when the Army re-chambered thousands of type 99s in 30-06 and issued them to ROK troops. Even if someone DID manage to chamber and fire an 06 round in the 99, it wouldn't hurt the rifle, which can easily handle any pressures the 06 can generate. And you're pushing a .308" diameter bullet down a .311" bore. There will be gas blowby in the barrel which lowers pressures. I have fired many 308/ 7.62 Nato rounds in my type 99. The accuracy isn't so good, and the cases have almost no neck left...but there is nothing dangerous about it. Just make sure they feed out of the magazine so the extractor can hold them against the breech face.
I can confirm this, I wasn't able to chamber a 30-06 cartridge when I purchased a sporterized 7.7 Arisaka. Was hopeful that it had been rechambered, but it probably would have shot poorly with the oversized bore, anyway.If the chamber is anywhere near spec on the 99, it is literally impossible to chamber an 06 round.
Likewise here. The 7.65 Argie rounds will shoot quite accurately because the bullet is the proper .311" diameter. 300 savage will also work, although you will end up with a straight walled case. As long as the rounds are fed out of the magazine and held by the extractor it is safe. On my gun, a 308 will not quite chamber. The Japanese round has a slight taper, the 308 does not. What happens is the forward edge of the shoulder on the 308 touches the slightly tapered chamber walls and it binds. With the bolt handle almost closed. My solution is simple. I remove the decapper on my full length 7.7 dies and size the loaded 308 round, squeezing the shoulder of the case just a tiny bit. Barely enough to be visible. Now the rounds chamber easily.I had one when I was a teenager. I could find 7.7 anywhere but I also had a 91 Argentine that took 7.65. I shot a good many 7.65 out of my Arisaka. Just a thin ring was all that was left of the neck. They were quite accurate tho. I'm not sure what would have happened if one of my cases had been short.
The re-chambered guns were clearly marked on the left side of the receiver. You could try the .308/ 7.62 mm option. Some 99s will chamber the 308 easily with no trouble. Others wont even come close. The Japanese chambers were not as uniform as ours, especially later in the war. Tooling was often used beyond its service life in the attempt to save production costs. Chamber reamers were certainly on this list.I can confirm this, I wasn't able to chamber a 30-06 cartridge when I purchased a sporterized 7.7 Arisaka. Was hopeful that it had been rechambered, but it probably would have shot poorly with the oversized bore, anyway.