MGD PM-9
- Category
- Submachine Gun
- Barrel
- 213 mm
- Weight, empty
- 2.53 kg
- Introduced
- 1954
About
What it is, and why it matters
The MGD PM-9 is a French open-bolt submachine gun designed in the early 1950s by Louis Debuit at Etablissements Merlin & Gerin in Grenoble. It is notable for its highly unconventional operating system: an off-axis delayed blowback action using a rotating flywheel housed in a circular extension on the right side of the receiver, coupled to a clock-style spiral mainspring reminiscent of the Lewis gun. The shooter cocked the weapon by rotating the flywheel roughly 180 degrees, which stored energy in the spring and retracted the bolt. Chambered in 9x19mm Parabellum and fed from folding-housing MP38/MP40-compatible 32-round magazines, it featured a side-folding wire stock for compactness.
The MGD acronym combines the maker's initials (Merlin & Gerin) with those of the designer, Debuit. Its clock-spring flywheel delay is one of the most eccentric SMG mechanisms ever to reach production, and surviving examples are prized collector rarities.
The unusual flywheel-and-spiral-spring mechanism made the PM-9 mechanically complex and expensive to produce, which doomed it commercially. It saw no confirmed military or police adoption.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- Etablissements Merlin & Gerin
- Category
- Submachine Gun
- Country
- France
- Status
- Discontinued
- Produced
- 1954 to 1956
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 213 mm
- Overall length
- 659 mm
- Weight, empty
- 2.53 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Delayed blowback
- Firing mechanism
- Hammer fired
- 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
- Blued
BallisticsFrom the service cartridge, not a handload.
- Muzzle velocity
- 400 m/s
- Effective range
- 100 m
- Rate of fire
- 750 rpm
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.
Open bolt- Rotating flywheel delay
- Spiral mainspring
Folding magazine housing
Side folding stock
Mp40 magazine compatible
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 | 2.53 kg | 3.18 kg | Lighter than about 80% |
| Overall lengthAmong 200 9x19mm Parabellum submachine guns | 659 mm | 723 mm | Shorter than about 70% |
| Barrel lengthAmong 202 9x19mm Parabellum submachine guns | 213 mm | 213 mm | Near the median |
| Magazine capacityAmong 204 9x19mm Parabellum submachine guns | 32 | 32 | Holds more rounds than about 60% |
Answers
Questions about the MGD PM-9
How much does the MGD PM-9 weigh?
The MGD PM-9 weighs 2.53 kg (5.58 lb) empty.
What caliber is the MGD PM-9?
The MGD PM-9 is chambered in 9x19mm Parabellum.
How many rounds does the MGD PM-9 hold?
The MGD PM-9 holds 32 rounds, fed from a detachable box magazine.
How long is the MGD PM-9?
The MGD PM-9 is 659 mm (25.9 in) long overall, with a 213 mm (8.39 in) barrel.
Who makes the MGD PM-9?
The MGD PM-9 is made by Etablissements Merlin & Gerin (France). It was designed by Louis Debuit.
When was the MGD PM-9 introduced?
The MGD PM-9 was introduced in 1954 and discontinued in 1956.
How does the MGD PM-9 operate?
The MGD PM-9 uses a delayed blowback action, and its firing mechanism is hammer fired.
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.
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/mgd-pm9' \ --header 'X-API-Key: your_key'{ "id": "mgd-pm9", "name": "MGD PM-9", "manufacturer": { "id": "merlin-gerin", "name": "Etablissements Merlin & Gerin", "countryCode": "FR", "foundedYear": 1920, "website": null, "logoUrl": null, "description": null, "status": null, "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-07-19 22:59:14", "updatedAt": "2026-07-19 22:59:14", "version": "c74ac3bab147683b55d39a52a9a6eb29b90ed9ac14409af4e4225ceb2b392296" }, "category": { "id": "submachine-gun", "name": "Submachine Gun", "description": "Automatic firearms chambered in pistol calibers" }, "country_of_origin": "FR", "year_introduced": 1954, "barrel_length_mm": 213, "weight_empty_g": 2530, "action_type": "delayed_blowback"}