Mendoza HM-3S
- Category
- Submachine Gun
- Barrel
- 225 mm
- Weight, empty
- 2.69 kg
- Introduced
- 1998
About
What it is, and why it matters
The Mendoza HM-3S is a Mexican semi-automatic submachine gun, the police and private-security variant of the select-fire HM-3. Designed by Hector Mendoza and built by Productos Mendoza S.A., it uses a simple blowback action firing 9x19mm Parabellum (and .380 ACP for security use) from a closed bolt. The compact weapon employs a wrap-around bolt over a fixed barrel, a folding stock, a grip safety, and a 32-round detachable box magazine, making it well suited to close-quarters and urban operations.
The HM-3 line springs from a Mexican firearms dynasty: Hector Mendoza designed it following in the footsteps of his father Rafael Mendoza, whose light machine guns armed the Mexican military for decades. Tight Mexican export laws have kept the gun almost unknown outside its home country.
The HM-3S semi-automatic variant fires from a closed bolt with polymer furniture and a U-shaped cocking handle, distinguishing it from the earlier open-bolt select-fire HM-3. Mexican export restrictions have limited its international availability. Also produced in a compact .380 ACP 'Bulldog' configuration.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- Productos Mendoza S.A.
- Category
- Submachine Gun
- Country
- Mexico
- Status
- In production
- Produced
- 1998
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 225 mm
- Overall length
- 635 mm
- Weight, empty
- 2.69 kg
- Weight, loaded
- 3.35 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Blowback
- Firing mechanism
- Closed bolt
- Trigger
- Single stage
- Capacity
- 32
- Magazine
- Detachable box
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Steel
- Barrel
- Steel
- Stock
- Steel
- Finish
- Phosphate
BallisticsFrom the service cartridge, not a handload.
- Effective range
- 100 m
Trajectory
What the round does downrange
Solved from the muzzle figures and the bullet. The dashed rule is the effective range on the record, and the crosses are the steps the solver returned.
Features
What it has
What the record lists as fitted, drawn from the catalogue.
Folding stock
Wrap around bolt
Polymer furniture
Fixed barrel
Compact
Standing
How it compares
Each figure against the firearms of the same type and cartridge that record it, or of the same type where that cartridge has too few. Positions are read to the nearest tenth.
| Measurement | This firearm | Median | Position |
|---|---|---|---|
| Empty weightAmong 201 9x19mm Parabellum submachine guns | 2.69 kg | 3.18 kg | Lighter than about 70% |
| Overall lengthAmong 200 9x19mm Parabellum submachine guns | 635 mm | 723 mm | Shorter than about 80% |
| Barrel lengthAmong 202 9x19mm Parabellum submachine guns | 225 mm | 213 mm | Longer than about 60% |
| Magazine capacityAmong 204 9x19mm Parabellum submachine guns | 32 | 32 | Holds more rounds than about 60% |
Answers
Questions about the Mendoza HM-3S
How much does the Mendoza HM-3S weigh?
The Mendoza HM-3S weighs 2.69 kg (5.93 lb) empty and 3.35 kg (7.39 lb) loaded.
What caliber is the Mendoza HM-3S?
The Mendoza HM-3S is chambered in 9x19mm Parabellum and .380 ACP.
How many rounds does the Mendoza HM-3S hold?
The Mendoza HM-3S holds 32 rounds, fed from a detachable box magazine.
How long is the Mendoza HM-3S?
The Mendoza HM-3S is 635 mm (25.0 in) long overall, with a 225 mm (8.86 in) barrel.
Who makes the Mendoza HM-3S?
The Mendoza HM-3S is made by Productos Mendoza S.A. (Mexico). It was designed by Hector Mendoza.
When was the Mendoza HM-3S introduced?
The Mendoza HM-3S was introduced in 1998.
How does the Mendoza HM-3S operate?
The Mendoza HM-3S uses a blowback action, and its firing mechanism is closed bolt.
Compatibility
Which parts fit this firearm
Studio
Every part that mounts on this, resolved
Not a list the maker typed out: the answer comes from the mounts this firearm exposes and the interface each part needs, so it stays right when either one changes.
- Every part that mounts on any firearm in the catalogue
- Interface standards, platforms and fit overrides
- The same answers through the API and the MCP server
Requires a signed-in GunSpec account on the Studio plan. The answer is computed per part, so it is not part of the public record.
Provenance
What the record holds
Every figure above was taken from one of these pages. The confidence reflects how much of the record came from a page a claim can be checked against.
In service
- Mexican Armed Forces
- Mexico
- Mexican police and private security forces
- Mexico
Provenance
Confidence in this record
72%
Stockists
Where to buy
Offers link straight to the shop. GunSpec never takes the order.
No shop has listed this firearm yet
Stock and prices come from the shops themselves. If you sell this firearm, you can list it and it appears here.
List a firearmMCP
Ask an assistant about it
The same record, reached the way a person asks for it rather than the way a program does.
Ask GunSpec
Works with
Point an MCP client at GunSpec and it answers from the catalogue rather than from memory. A free key covers the read tools.
API
The call that returns this record
The same fields, in the same units, from the same endpoint the page reads.
curl --request GET \ --url 'https://api.gunspec.io/v1/firearms/mendoza-hm-3s' \ --header 'X-API-Key: your_key'{ "id": "mendoza-hm-3s", "name": "Mendoza HM-3S", "manufacturer": { "id": "productos-mendoza", "name": "Productos Mendoza S.A.", "countryCode": "MX", "foundedYear": 1911, "website": "https://www.mendozafa.com", "logoUrl": null, "description": "Mexican firearms and air gun manufacturer founded in 1911 by Rafael Mendoza Blanco. Based in Xochimilco, Mexico City. Produces firearms including the HM-3 submachine gun used by Mexican police, semi-automatic rifles, and air guns.", "status": "active", "defunctYear": null, "stateOwned": null, "makesFirearms": true, "parentId": null, "predecessorId": null, "createdAt": "2026-06-21 23:00:46", "updatedAt": "2026-06-21 23:00:46", "version": "3a4138b1edd3f2a806f09e6c45c431d7eb2a2b130a11412e2abd4902db13cf90" }, "category": { "id": "submachine-gun", "name": "Submachine Gun", "description": "Automatic firearms chambered in pistol calibers" }, "country_of_origin": "MX", "year_introduced": 1998, "barrel_length_mm": 225, "weight_empty_g": 2690, "action_type": "blowback"}