While the Japanese situation on ammunition types for pistols and SMGs was good, it was a nightmare when it came to rifles and machineguns. Apart from using 6.5mm and 7.7mm ammo, the Japanese used multiple types of 7.7mm ammo (rimmed, rimless and semi-rimmed) which were generally incompatable with each other..
Pistols
Model 26, 9mm Japanese (1893): This break-open revolver used an unique 9mm round and was the first modern Japanese military pistol. It also was double-action only, which combined with a very heavy trigger pull, made it hard to fire quick, accurate shots (apply the -2 for double-action revolvers to all shots). Treat it as the Enfield No. 2 Mk I revolver, with Wt 2.2.
1904 Nambu, 8mm Nambu: This was the forerunner of the 14 Shiki. Other than using a grip safety instead of a manual safety (meaning the 1904 Nambu won't fire if not gripped firmly), it is the same as the 14 Shiki, but Malf Crit. While not an official service weapon in WWII, numbers found their way into use.
Baby Nambu, 7mm Nambu (1904): This 7mm pistol was basically a smaller version of the 1904 9mm Nambu, Treat it as the Type 14, but with Dam 2d- Wt 1.4, Shots 6+1, Holdout +0. A nonstandard pistol, it was usually only found with air crews.
Type 25, 8mm Nambu (1936): This was a 14 Shiki with an enlarged trigger guard allowing the firer to wear thick gloves.
Rifles
Type 38 carbine, 6.5mm Arisaka (1905): This was a 6” shorter version of the 38 Shiki rifle (p.W:95, under 99 Shiki). Treat as the 38 Shiki, but dam 5d+2, Wt 7.3. Mainly used by cavalry, some were later modified for paratrooper use by having a hinged buttstock that could be folded.
Type 44 carbine, 6.5mm Arisaka (1911): This was the same as the Type 38 carbine, but was heavier (Wt 8.9) due to a permanently attached spiked bayonet that folded back along the forestock. It was primarily used by cavalry.
Type 97, 6.5mm Arisaka: The 38 Shiki rifle fitted with a x2.5 scope (+1 Acc), for use as a sniper rifle
99 Shiki: In addition to the information on p.W95, the rifle was fitted with a folding monopod, which gives a +1 for braced fire from the prone position. Also, it had an unusual rear sight with folding arms to allow accurate fire at aircraft by giving a proper lead; at the GM's option, a firer can get +1 Acc vs flying targets.
Type 99 sniper rifle, 7.7mm Arisaka (1942): This was a standard 99 Shiki issued with a 4x scope (+2 Acc).
Type 99 short rifle, 7.7mm Arisaka (1939): Essentially a carbine version of the 99 Skiki, it was over a foot shorter and half a pound lighter. Treat it as the 99 Shiki but Dam 6d+1 and Wt 8.6.
Type 2 rifle, 7.7mm Arisaka (1942): This was a Type 99 short rifle designed for take-down. Treat as the Type 99 short rifle, but Wt. 8.9.
Type 5, 7.7mm Arisaka (1945): An attempt to copy the American M-1 Garand, only about 20 were made before the war ended. Chambered for the standard 7.7mm round, it differed from t he M-1 by loading from two 5-round stripper clips instead of a single 8 round en bloc clip. The Type 5 functioned poorly, primarily due to the low quality materials available to the Japanese in 1945.
Submachineguns
Bergmann 1920, 7.63mm Mauser: This was the Bergmann 18/I modified to take a 50-round box magazine and fitted with a lug for the standard rifle bayonet. It was used in small numbers by the SNLF in the Philippines in 1941-42. Treat it as the MP 28/II (p.W:IC63), except Dam 3d-1-, Wt 11.8 and Awt 2.3.
100 Shiki: Some were fitted with bipods and most had bayonet lugs. About half had folding stocks. In 1944, a version with RoF 13 was introduced.
Machineguns
Type 3, 6.5mm Arisaka (1914): Based on the Hotchkiss Model 1900, this reliable heavy machinegun was fired from a tripod. It used 30 round metal clips that required an oiling mechanism in the gun. Treat is as the 11 Shiki, but Malf Crit, Wt 62/60, Awt 2.4, Shots 30, ST 29T.
Type 92, 7.7mm SR (1932): This is the Type 3 chambered for the more powerful 7.7mm round and was Japan's most common HMG in WWII. Due to it's distinctive sound, it was known to Allied troops as the “Woodpecker.” Treat it as the Type 3, but Dam 6d+2, Acc 8, 1/2D 1000, Max 3900.
Type 1, 7.7mm SR (1942): This was a lightened Type 92, weighing only 70 lbs with tripod. The barrel could be changed faster and RoF was 9.
Type 91, 6/5mm: The 11 Shiki adapted for use in a tank.
Type 92, .303 British: Confusingly enough, there was a second Type 92 MG in the Japanese inventory, which was a copy of the Lewis MG. It was used by the Army and Navy, both as an AA gun and as a flexible mount in aircraft Note that it did not use the same ammo as other Japanese 7.7mmweapons.
Type 93, 13.2mm Hotchkiss: This was a copy of the Hotchkiss Modele 14 13.2mm (p.W:RH38). It was normally found in dual AA mounts.
Grenades and Grenade Launchers
Type 97 grenade (1937): The standard Japanese hand grenade of WWII, it differed from the 91 Shiki in lacking a propellant charge (so it could not be used in a grenade launcher) and fuse delay was 4-5 seconds. It was otherwise the same as the 91 Shiki, with Wt 1.
Type 99 grenade (1939): Unlike the earlier grenades, the Type 99 had a smooth casing. It could be used as either a hand grenade or rifle grenade. Wt 0.65, Delay 4-5.
Type 10 grenade launcher (1921): The predecessor of the 89 Shiki, it used a smoothbore barrel 4” shorter than the 89 Shiki. Range was 65 to 175 yards and was set by turning a gas valve. It used the 91 Shiki grenade, as well as smoke, flare and signal rounds. Wt 5.7.
Sources
Small Arms of the World, Smith and Smith, Galahad Books, 1973
Japanese Army Handbook: 1939-1945, George Forty, Sutton Publishing, 2002
The Encyclopedia Of Weapons Of WWII, Bishop, Barnes & Noble, 1998