I’ve put together a brief summary of the Ho-Ri’s shell types, so I’m sharing it here. This includes both the shells that were planned in the early stage and those that were actually fired by the Ho-Ri gun, from its first firing test on December 20, 1944, to its last recorded firing on June 27, 1945.
For reference, the original drawings for the Ho-Ri’s HE and AP shells come from the Ka-To research notes. According to Ka-To research notes, the Ka-To and Ho-Ri used exactly the same shell designs.
1. Type 91 Pointed Shell (modified driving band) (HE)
九二式十加九一式尖鋭弾 (弾帶改修セルモノ)
Weight: 15.760 kg
Explosive filler: 2.520 kg
Fuze: Type 88 instantaneous fuze, Type 88 short-delay fuze
Muzzle velocity:
667.2 m/s (propellant charge: 5.000 kg)
848.7 m/s (propellant charge: 6.400 kg)
912.8 m/s (propellant charge: 6.800 kg)
Firing period: December, March, May
Number fired: 86
While the projectile itself was identical to that used in the Type 92 cannon, it was fired as a complete round rather than as separate-loading ammunition. In addition, its single driving band was modified into a double-band configuration before use.
Since the standard propellant charge had not yet been fixed at the time, it was tested with several different charge weights.
2. Experimental high-power 10 cm cannon cylindrical shell
試製大威力十加円壔弾
Weight: 16 kg
Explosive filler: unknown (filled with sand during testing)
Muzzle velocity: not measured
Firing period: March, May
Number fired: 86
This was a test shell originally used for the high-power 10 cm cannon that predated the Ho-Ri gun’s development. Detailed information is unknown, but from the context, it appears to have been a cylindrical projectile intended to verify internal ballistic performance.
3. Experimental pointed shell (HE)
試製尖鋭弾
Design weight: 15.76 kg
Test weight: 15.650 kg
Explosive filler: 2.52 kg
Fuze: Type 88 instantaneous fuze, Type 88 short-delay fuze
Muzzle velocity: 715.9 m/s (propellant charge: 5.1 kg)
Firing period: June
Number fired: 69
This shell was built to a design almost identical to the Type 91 HE shell, and it is currently the only surviving physical Ho-Ri projectile.
4. Experimental (Type 4) armor-piercing shell (AP)
試製(四式)徹甲弾
Design weight: 16.000 kg
Test weight: 15.640-16.240 kg (average: 16.022 kg)
Explosive filler: none
Muzzle velocity: 907.9 m/s (propellant charge: 6.45 kg)
Firing period: June
Number fired: 56
Like the other Type 4 AP shells, this was a solid AP round without explosive filler. The designation “Type 4” does not actually appear in the Ho-Ri research notes, where it is simply called an experimental AP. I borrowed the “Type 4” designation from the Ka-To research notes.
5. Substitute shell
代用弾
Weight: 16 kg
It was planned in the early design stage, but does not appear to have ever been produced. It was supposed to be based on the Type 14 substitute shell.
6. Armor-piercing shell (APHE)
徹甲弾
Weight: 16 kg
Explosive filler: unknown
Fuze: Experimental Type 1 armor-piercing medium Mk.3 base fuse
Ogive radius: 200 mm
Projectile length: 315 mm
This is the shell commonly known as the Type 2 APHE. In fact, this AP shell was not used during the Ho-Ri gun tests. The original Experimental Type 2 AP shell (試製二式徹甲弾) had been developed for the Type 92 Cannon, and the Ho-Ri’s APHE was originally supposed to be made on the basis of that shell, but it seems to have been postponed or canceled at some point.
That said, I’m still not sure whether the Ho-Ri using Type 2 APHE in WT should necessarily be considered an error. The Type 92 shells were essentially compatible with the Ho-Ri gun, and adapting them only required the simple modification of adding one more driving band and fitting them into cartridge cases.
