The 7.7x58mm Japanese or 7.7x58mm Arisaka cartridge was developed by Imperial Japan for use in its machine guns and rifles beginning in the 1930s. It was intended to replace the 6.5x50mm Japanese cartridge but never fully replaced it by the end of World War II.
With untold numbers of Japanese rifles having been brought back by US servicemen after the end of the war, many of these rifles remain in the United States. Their popularity has never been that great among mainstream collectors, partially due to difficulty in sourcing ammunition, so prices for these rifles are generally pretty cheap, especially when compared to more popular rifles such as German Mausers.
The Arisaka rifles chambered in 7.7x58 are essentially a Mauser-type action, and their reputation is for incredible action strength due to the use of high quality steel. This holds for rifles produced through about mid-war. Rifles produced towards the end of the war saw a noticeable deterioration in quality, with some last ditch rifles built towards the end of the war being produced out of cast iron. These last ditch rifles, along with training rifles, are not safe to shoot with any cartridge. They are popular with some collectors of Japanese rifles, but should not be fired.
Care will have to be taken with any Japanese rifle to ensure that it is chambered in its original Japanese configuration. Many were rechambered upon arrival to the US, with the 7.7x58 rifles sometimes having the chambers reamed with a .30-06 chamber reamer to allow the use of unconverted .30-06 brass.
The 7.7x58 features a bullet diameter of .312”, just like the .303 British, 7.62x54R, and 7.65x53 Belgian/Argentine cartridges. Case dimensions are very similar to the 8x57mm Mauser cartridge, and performance is in the same class as the 8mm Mauser and .30-06.
The original loadings featured 175-grain bullets traveling at around 2,400 feet per second and 200-grain bullets at around 2,200 feet per second, for about 2,200 foot-pounds of muzzle energy. Modern load data shows performance of 150-grain bullets at 2,650 feet per second, and 180-grain bullets at 2,550 feet per second, for up to 2,600 foot-pounds of muzzle energy. That performance is achieved at relatively low pressures of only 42,000 psi, well below the capability of the Arisaka rifle action.
This kind of performance means that the 7.7x58 is capable of taking just about any big game in North America, provided the right types of bullets are used. Selection of .312” bullets is rather limited in the US, but there are numerous options available.
Brass for the 7.7x58 is available from Prvi Partizan and Norma, while bullets are produced by Sierra, Hornady, Woodleigh, and others. Brass can also be formed from either .30-06 or 8mm Mauser brass. Given the oversized chambers in Arisaka rifles, brass often has a tendency to bulge near the base.
If you have an Arisaka rifle, it’s certainly an effective hunting or self defense rifle, certainly just as effective as any Mauser rifle. And if you already have reloading supplies for any of the other Russian/British/European fat .30-caliber cartridges, you should be just fine reloading for the 7.7x58. But if you’re looking for something with readily available ammunition in a SHTF type of scenario, the 7.7x58 should probably not be your first choice.