German MP-40 Sub Machine Gun

Happy Friday readers! This week for Firearm Friday we are looking at something iconic and pivotal in small arm automatic firearm production. The German Maschinenpistole 40 more commonly known as the MP-40

The MP40 occupies an important place in the history of small arms as a purpose-built wartime submachine gun that balanced economy of manufacture with battlefield utility. Developed from the earlier MP38, the MP40 refined and simplified its predecessor’s layout so it could be produced in far greater numbers.

The design deliberately moved away from heavy machined components toward stamped and folded sheet steels, rivets and welded assemblies; plastic materials such as early Bakelite were used for non-structural parts. Those choices reduced production time and cost while keeping tolerances and ergonomics good enough for a broadly reliable service weapon. The MP40’s silhouette short barrel, compact receiver, and a generally utilitarian appearance is as much a product of those manufacturing priorities as of its intended tactical role.

Technically, the MP40 is a simple blowback submachine gun that fires from an open bolt. When the trigger is pressed the cocked bolt travels forward, strips a round from the removable box magazine, chambers it and fires; recoil forces drive the bolt rearward, extracting and ejecting the spent case and cocking the bolt for the next shot.

The open-bolt arrangement simplified the firing mechanism and helped cool the chamber between bursts, but it limited fine accuracy at long ranges because the bolt’s forward movement just before firing introduces a small but significant disturbance. The MP40 was chambered in 9mm and normally used a 32-round detachable box magazine. Its practical effective engagement window was at close ranges where the 9mm cartridge and controllable rate of fire offered the most tactical advantage typically well inside 200 metres and most often within 75–150 metres in combat conditions.

Ergonomics and handling were strengths for the MP40. Its relatively low fire rate made it controllable in short bursts; many crews could deliver effective suppressive or precision short-burst fire in confined spaces. The controls were deliberately simple and straightforward: a folding metal stock made the weapon compact for transport and use inside vehicles, armoured fighting-vehicle crews appreciated its stowability, and paratroops and assault troops found the compactness an advantage in close combat. Sights were basic, a fixed front post and a simple rear notch or flip sight calibrated for short range reflecting the weapon’s close-quarters purpose rather than long-range marksmanship.

Over the course of the war the MP40 underwent incremental simplifications as production pressures rose. Early components and finish work were of higher quality; later wartime examples show rougher stamping, fewer finishing touches and small design changes intended to save steel, time or skilled labour. Field experience also produced practical modifications and varied kit included: slings, magazine pouches, cleaning rods, and occasionally improvised mounts or attachments made by soldiers in the field. Magazines could be sensitive to dirt and damage; soldiers were trained to keep the feed lips and followers clean, and the magazines themselves were a frequent maintenance item.

Tactically, the MP40 found its niche in German formations as a weapon for squad leaders, vehicle crews, paratroopers, assault detachments and defenders in urban or close terrain. Its automatic fire and handy size made it excellent for trench raids, room-clearing, vehicle interior defence and rear-area security. It was not intended to replace rifles in general infantry formations but to provide a high-volume automatic option to complement bolt-action and semi-automatic rifles. In urban or close terrain, where rapid, controllable fire is decisive, the MP40 outperformed rifles and provided infantry elements a degree of suppressive fire they otherwise lacked.

There were limitations. The open-bolt design, while simple, reduced precision at longer ranges and made the weapon less suitable for aimed, single-shot fire at distance. Magazine reliability was occasionally an issue under harsh conditions; feed problems could arise if the magazine lips or follower were damaged or clogged with debris. The fixed iron sights and the 9mm cartridge also limited long-range performance compared with rifle calibres. Despite these liabilities, in the role it was designed for the MP40 remained effective, a reliable close-quarters platform with a low training burden for basic operation.

The MP40 also had an outsized cultural and post-war legacy. Its image became synonymous with German infantry in photographic and cinematic depictions of World War II, and surviving examples were widely captured, reused and sometimes copied after the conflict. For collectors and historians the MP40 presents interesting variation: wartime finish differences, manufacturer marks and serial ranges, and field-modifications help provenance and valuation. Original accessories magazines, slings, cleaning kits and shoulder stocks  are important to command premium interest. Preservation of originals requires careful attention: wooden or Bakelite components can be brittle, steel parts benefit from rust control and correct conservation techniques, and the preservation of original finishes and markings is usually more desirable than refinishing.

From the engineering viewpoint, the MP40 exemplifies wartime pragmatism: the design accepted modest compromises in long-range accuracy to gain simplicity, repeatability and manufacturability. That tradeoff allowed armed formations to field a large number of compact automatic weapons suited to a mechanised, close-combat battlefield. For students of small arms the MP40 remains a clear case study in how manufacturing technology, tactical doctrine and battlefield needs converge to shape weapon design.

For those handling, restoring or collecting MP40s today, a few practical notes: inspect magazines and feed lips carefully for damage, verify matching parts and visible maker’s marks when provenance matters, preserve wood and early plastics with appropriate, non-invasive stabilisers, and avoid crude cleaning that removes original finish or markings. When evaluating serviceability or display authenticity, accessories and correct wartime fittings are often as important as the receiver condition itself.

In sum, the MP40 is more than a period icon, it’s an instructive example of engineering priorities altered by war. It demonstrates how a weapon can be optimized for a specific tactical envelope and manufactured under industrial constraints to deliver broad operational capability. Its combination of mechanical simplicity, compact handling and historical visibility keeps the MP40 central to discussions of World War II small arms design, usage and collecting.

Our MP-40 is located on our “World War” wall and is accompanied by other sub machine guns from that time period, with the MP-40 being fairly easy to recognise. Our MP-40 is non operating however is still a display piece all on its own.