Interdynamic MP-9
- Category
- Submachine Gun
- Barrel
- 173 mm
- Weight, empty
- 1.70 kg
- Introduced
- 1983
About
What it is, and why it matters
The Interdynamic MP-9 is a Swedish-American blowback-operated, closed-bolt submachine gun chambered in 9x19mm Parabellum. Designed by Swedish engineer George Kellgren (Goran Kjellgren) and built by Interdynamic AB of Stockholm, with US production through Interdynamic USA of Miami, it was conceived as an inexpensive, fast-firing weapon drawing on the layout of the Carl Gustav m/45. Fed from detachable box magazines of up to 32 rounds and fitted with a collapsible wire stock, the select-fire MP-9 cycled at roughly 1,000 rounds per minute. Interdynamic failed to attract any military buyers, and only a few dozen registered select-fire examples were ever produced. The design was instead reworked for the US civilian market as the open-bolt semi-automatic KG-9 pistol, which went on to spawn the Intratec KG-99 and the notorious TEC-9.
The MP-9 is the obscure Swedish ancestor of one of America's most notorious firearms. Designer George Kellgren could not interest any government in his cheap submachine gun, so partner Carlos Garcia took it to the US market as the semi-automatic KG-9. After the ATF reclassified the open-bolt KG-9 as a machine gun in 1982, the design was reworked into the closed-bolt KG-99 and then the Intratec TEC-9, a fixture of 1990s crime imagery. Kellgren went on to found Grendel and later Kel-Tec, designing far more respected weapons such as the SUB-2000 and KSG.
The MP-9 is the original select-fire submachine gun from which the civilian KG-9 pistol (and later the TEC-9) was derived by removing the stock and converting to semi-automatic-only fire. Reported figures vary between sources; weight is cited around 1.7 kg, barrel length around 173 mm, and overall length 328 mm with the stock collapsed and 541 mm extended. Fewer than 50 select-fire MP-9s were built, with as few as roughly 24 in the full select-fire-with-stock configuration, making genuine examples extremely rare. The overall_length_mm field records the stock-extended length; the stock-collapsed length is approximately 328 mm.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- Interdynamic AB
- Category
- Submachine Gun
- Country
- Sweden
- Status
- Discontinued
- Produced
- 1983 to 1984
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 173 mm
- Overall length
- 541 mm
- Weight, empty
- 1.70 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Blowback
- Firing mechanism
- Closed bolt
- Trigger
- Single action
- Capacity
- 32
- Magazine
- Detachable box
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Stamped steel
- Barrel
- Steel
- Stock
- Steel
- Finish
- Phosphate
BallisticsFrom the service cartridge, not a handload.
- Muzzle velocity
- 396 m/s
- Muzzle energy
- 584 J
- Effective range
- 55 m
- Maximum range
- 150 m
- Rate of fire
- 1000 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.
Select fire
Collapsible stock
Barrel shroud
Stamped steel receiver
Extended magazine compatible
Threaded barrel
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 | 1.70 kg | 3.18 kg | Among the lightest tenth |
| Overall lengthAmong 200 9x19mm Parabellum submachine guns | 541 mm | 723 mm | Shorter than about 90% |
| Barrel lengthAmong 202 9x19mm Parabellum submachine guns | 173 mm | 213 mm | Shorter than about 90% |
| Magazine capacityAmong 204 9x19mm Parabellum submachine guns | 32 | 32 | Holds more rounds than about 60% |
Its place in the rankings
Answers
Questions about the Interdynamic MP-9
How much does the Interdynamic MP-9 weigh?
The Interdynamic MP-9 weighs 1.70 kg (3.75 lb) empty. It is the 7th lightest of 201 9x19mm Parabellum submachine guns in the catalogue.
What caliber is the Interdynamic MP-9?
The Interdynamic MP-9 is chambered in 9x19mm Parabellum.
How many rounds does the Interdynamic MP-9 hold?
The Interdynamic MP-9 holds 32 rounds, fed from a detachable box magazine.
How long is the Interdynamic MP-9?
The Interdynamic MP-9 is 541 mm (21.3 in) long overall, with a 173 mm (6.81 in) barrel.
Who makes the Interdynamic MP-9?
The Interdynamic MP-9 is made by Interdynamic AB (Sweden). It was designed by George Kellgren.
When was the Interdynamic MP-9 introduced?
The Interdynamic MP-9 was introduced in 1983 and discontinued in 1984.
How does the Interdynamic MP-9 operate?
The Interdynamic MP-9 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.
Provenance
Confidence in this record
60%
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/interdynamic-mp9' \ --header 'X-API-Key: your_key'{ "id": "interdynamic-mp9", "name": "Interdynamic MP-9", "manufacturer": { "id": "interdynamic", "name": "Interdynamic AB", "countryCode": "SE", "foundedYear": null, "website": null, "logoUrl": null, "description": null, "status": null, "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-06-21 23:00:46", "updatedAt": "2026-06-21 23:00:46", "version": "9ee9d570da6a74a3b1ce412d68cea7d98c9c90d8e59c605cd65a7604e1ea2cac" }, "category": { "id": "submachine-gun", "name": "Submachine Gun", "description": "Automatic firearms chambered in pistol calibers" }, "country_of_origin": "SE", "year_introduced": 1983, "barrel_length_mm": 173, "weight_empty_g": 1700, "action_type": "blowback"}