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 · 134

Ho-204 37mm 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. 37mm Browning Aircraft H0-204 Machineguns/Cannons.

What this entry requires

  • INFOATF states no date; production was about 1944–1945.
  • INFOStill an NFA firearm; only registered examples transfer, with ATF approval (26 U.S.C. 5812, 5861).

Editorial facts · Our research

Country
Japan
Manufacturer
Chūō Kōgyō (Ōmori); Nagoya Army Arsenal¹
Type
Machinegun
Action
Select-fire / auto
Caliber
37mm
Made
1944–1945production; ATF states no date²
Service
Military
Search listings ↗Check a specific gunReport an error ↗

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: Medium · Last revised 18 October 2026 (Evidence pass) · How we rate confidence
References
  1. Wikipedia, “ホ204” ↗, maker: 製造: 大森中央工業 (developed and manufactured by Ōmori Chūō Kōgyō; prototype completed June 1943); ja ホ155-I: from late 1944 the Atsuta works of the Nagoya Army Arsenal switched to producing the Ho-204
  2. Wikipedia, “ホ155-I” ↗, years (estimate: partly supports it): after October 1944 the Atsuta works (Nagoya Army Arsenal) was turned over to Ho-204 production; end year 1945 is our estimate
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: High → Medium. Re-rated after its references were re-checked and some details couldn't be confirmed.
  2. Evidence passMaker: Japanese Army arsenals → Chūō Kōgyō (Ōmori); Nagoya Army Arsenal. Japanese Wikipedia (ホ204, ホ155-I)

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-204 cannon”. Text CC BY-SA 4.0. Retrieved October 2026.

FROM WIKIPEDIA

Ho-204 was a Japanese aircraft autocannon that saw limited use during World War II. It was the largest gun to see active service derived from the Model 1921 Aircraft Browning. It was used as upward-oblique armament in the Ki-46-III.