MGD PM-9
Etablissements Merlin & Gerin · Submachine Gun · Discontinued · 1954
Also known as: MGD PM9, Erma PM-9
Overview
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.
Specifications
| Weight (empty) | 2530 g (89.2 oz) |
| Overall Length | 659 mm (25.94") |
| Folded Length | 359 mm (14.13") |
| Barrel Length | 213 mm (8.39") |
| Action Type | Delayed Blowback |
| Firing Mechanism | Hammer Fired |
| Magazine Capacity | 32 rounds |
| Magazine Type | Detachable Box |
| Muzzle Velocity | 400 m/s (1312 fps) |
| Effective Range | 100 m (109 yd) |
| Rate of Fire | 750 rpm |
| Barrel Rifling | Right Hand |
| Frame Material | Steel |
| Barrel Material | Steel |
| Stock Material | Steel |
| Finish | Blued |
Calibers
- 9x19mm Parabellum · primary · 9mm NATO — also known as 9mm Luger, 9mm NATO, 9x19mm
Features
- Firing modes: Full Automatic
- Feed systems: Detachable Box Magazine
- Safety mechanisms: Manual Safety
- Features: Open Bolt, Rotating Flywheel Delay, Spiral Mainspring, Folding Magazine Housing, Side Folding Stock, Mp40 Magazine Compatible
Production
Production years: 1954-1956
Made in small numbers by Merlin & Gerin circa 1954-1955 in fixed- and folding-stock configurations; German firm Erma Werke built roughly 10 prototypes around 1956 under a licensing attempt before abandoning production due to cost and complexity.
Origin
Country of origin: France
Designer: Louis Debuit
Discontinued: 1956
Notes
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.
Background
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.