PrillrJ, Here are some exceprts from Francillion's Japanese Aircraft of the Pacific War.
Ki-43:Armament:
-Two 7.7mm Type 89 machine-guns (Ki-43-Ia)
-One 7.7mm Type 89 machine-gun and one 12.7mm Type 1 (Ho-103) machine-gun (Ki-43-Ib)
-Two 12.7mm Type 1 (Ho-103) machine-guns (Ki-43-Ic, Ki-43-IIa, Ki-43-IIb, Ki-43-II KAI and
Ki-43-IIIa-Two 20mm Ho-5 cannon (Ki-43-IIIb)
Production:A total of 5919 Ki-43s were manufactured as follows:
Nakajima Hikoki K.K. at Ota:3 Ki-43 prototypes (Dec 1938-Mar 1939)
10 Ki-43 Service trials aircraft (Nov 1939-Sept 1940)
716 Ki-43-I production aircraft (Apr 1941 - Feb 1943)
5 Ki-43-II prototypes (Feb-May 1942)
3 Ki-43-II Service trials aircraft (June-Aug 1942)
2492 Ki-43-II production aircraft (Nov 1942-Oct 1944)
10 Ki-43-IIIa prototypes (May 1944-Aug1945)
Tachikawa Hikoki K.K. at Tachikawa:2,629 Ki-43-II and Ki-43-IIIa production aircraft (May 1943 - Aug 1945)
2 Ki-43-IIIb prototypes (spring 1945)
Tachikawa Dai-Ichi Rikigun Kokusho at Tachikawa:49 Ki-43-IIa production aircraft (Oct 1942-Nov 1943)
I dont think the Ki-43 ever fired any weapon through the propeller hub. It would require a sustantial workaround to design a new engine and mountings. I have heard as many as three Ki-43-IIIb (20mm cannons in cowl) and as little as two built (according to the text above)
Hope this helps.
