Source: ATF P 5300.11 · Curios or Relics List · Jan 1972 – Apr 20253,573 entries · 4 sections
The C&R RegisterA finding aid to the ATF Curios or Relics List, for Type 03 collectors
C&R · IV · 135

Ho-301 40mm caseless aircraft cannon

Section IV: still an NFA firearm, also a curio or relic

Official wording

ATF P 5300.11 · APRIL 2025 EDITION · SECTION IV · VERBATIM · PDF P. 85 ↗

Japanese, cal. 40mm Caseless Aircraft Machineguns/Cannons.

What this entry requires

  • INFOATF states no date; production was about 1943–1945.
  • INFOStill an NFA firearm; only registered examples transfer, with ATF approval (26 U.S.C. 5812, 5861).

Editorial facts · Our research

Low editorial confidence. Some details below couldn’t be confirmed from independent sources. The ATF wording is unaffected. About confidence

Country
Japan
Manufacturer
Not stated (Japanese manufacture)
Type
Machinegun
Action
Select-fire / auto
Caliber
40mm caseless
Made
1943–1945production; ATF states no date
Service
Military
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Source

Official wording
ATF P 5300.11, April 2025 edition · Section IV · PDF p. 85 ↗ · ATF original ↗
Entries
1 line
Verbatim check
Checked against the PDF text before every release
Editorial facts
Confidence: Low · Last revised 18 October 2026 (Evidence pass) · How we rate confidence
References
None attached yet
Fact tags
  • ATF the ATF wording states it.
  • REF ¹ an outside reference supports it; the number points to the list of references.
  • ESTIMATE an approximate or indirect reading, for example the production range of the base model.
  • NO CITATION we haven’t attached a reference for this fact; it’s our editorial reading, not ATF’s.
Source checked
20 October 2026: ATF’s page still lists the April 2025 edition
Corrections
2 changes · see below

Correction history

  1. Evidence passEditorial confidence: Medium → Low
  2. Evidence passMaker: Japanese Army arsenals → Not stated (Japanese manufacture)

All corrections · How corrections work

Historical context

NO VERIFIED IMAGE AVAILABLEWe show only freely licensed images verified to depict this model. None has been found yet.

Summary: Wikipedia, “Ho-301 cannon”. Text CC BY-SA 4.0. Retrieved October 2026.

FROM WIKIPEDIA

The Ho-301 was a Japanese 40 millimeter caliber autocannon that saw limited use during World War II, on Japanese Army Nakajima Ki-44 and Kawasaki Ki-45 KAI aircraft. It was unusual in using caseless ammunition. Although the effective range of the cannon was only 150 meters (490 ft), the Ho-301 was light and rapid-firing for its caliber.