C&R · II · 362
MBA Gyrojet carbine, S/N B5057
Section II: curio or relic, still subject to the Gun Control Act
Official wording
ATF P 5300.11 · APRIL 2025 EDITION · SECTION II · VERBATIM · PDF P. 12 ↗
MBA Gyrojet Carbine, S/N B5057.
What this entry requires
- ATF REQUIRESYour serial number is one ATF listsATF: “S/N B5057”
- INFOATF states no date; production was about 1962–1970.
Editorial facts · Our research
- Country
United StatesBasis: no citation - Manufacturer
- MBAssociates, San Ramon, CABasis: outside reference ²
- Type
- RifleBasis: the ATF wording
- Action
- OtherBasis: no citation
- Caliber
- Not statedBasis: the ATF wording
- Made
- S/N B5057 only · c. 1962–1970production; ATF states no dateBasis: outside reference ¹
- Service
- Commercial
Source
- Official wording
- ATF P 5300.11, April 2025 edition · Section II · PDF p. 12 ↗ · ATF original ↗
- Entries
- 1 line
- Verbatim check
- Checked against the PDF text before every release
- Editorial facts
- Confidence: Medium · Last revised 17 October 2026 (Data-trust review) · How we rate confidence
- References
- 1. cdn.rockislandauction.com ↗, years: Gyrojet carbine with B-prefix serial, manufactured in the 1960s
- 2. Wikipedia, “Gyrojet” ↗, maker: developed by MBAssociates (MBA) in the 1960s
- 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
- 1 change · see below
Correction history
- Data-trust reviewEditorial confidence: Low → Medium. Re-rated after supporting references were added or re-checked.
Historical context
Image: Wikimedia Commons, “Gyrojet Rocket Carbine at the National Firearms Museum.jpg” by Joe Loong, CC BY-SA 2.0. Retrieved October 2026.
Summary: Wikipedia, “Gyrojet”. Text CC BY-SA 4.0.
FROM WIKIPEDIA
The Gyrojet is a family of unique firearms developed in the 1960s named for the method of gyroscopically stabilizing its projectiles. Rather than inert bullets, Gyrojets fire small rockets called Microjets which have little recoil and do not require a heavy barrel or chamber to resist the pressure of the combustion gases. Velocity on leaving the tube was very low, but increased to around 1,250 feet per second (380 m/s) at 30 feet (9.1 m). The result is a very lightweight and transportable weapon.