USMC Deployment
The Reising entered military service primarily because of uncertainty of supply of sufficient quantities of the Thompson submachine gun. In the testing stage, it won out over some other competing designs. It was very light and quite accurate in aimed fire, attributed to its better stock fit and intricate closed bolt, delayed blowback design, though its firepower was somewhat limited due to the 20-round capacity of its largest magazine. Most submachine guns fire from the open bolt position, meaning the full weight of the bolt slams forward when the trigger is pulled; with the Reising, only a lightweight firing pin striker moves when the trigger is pulled.
The U.S. Marines adopted the Reising in 1940 with 4,200 authorised per division with approximately 500 authorised per each infantry regiment.
During World War II, quantities of the M50 Reising gun were issued to U.S. Marine Corps personnel deployed to the Pacific theatre, and were used in the Solomon Islands campaign, including the battle for Guadalcanal. Most Reisings were originally issued to Marine officers and NCOs in lieu of a compact and light carbine, since the M1 carbine was not yet being issued to the Marines. Although the Thompson submachine gun was available, this weapon frequently proved too heavy and bulky for jungle patrols, and initially it too was in short supply.
The Paramarines and armoured crewmen were known to have been issued quantities of the folding stock M55, but the weapon's poorly designed wire-framed stock (which tended to fold while firing) soon earned the M55 a poor reputation. The 1st Marine Parachute Battalion were issued the weapon in New Zealand with other Marines only drawing their new Reisings onboard ship while headed towards Guadalcanal with a minimum of familiarization.
Unfortunately, the Reising was designed as a civilian police weapon and was not suited to the stresses of harsh battle conditions encountered in the Solomon Islands—namely, sand, saltwater and the difficulty in keeping the weapon clean enough to function properly. Tests at Aberdeen Proving Ground and Ft. Benning Georgia had found difficulties in blind-folded reassembly of the Reising, indicating the design was complicated and difficult to maintain. Many of the parts were hand fitted at the factory; this lack of parts interchangeability was not a problem for a civilian or police firearm, but it caused difficulty when Reisings were maintained in the field under combat conditions.
While more accurate than the Thompson, particularly in semi-automatic mode, the Reising had a tendency to jam. This was in part due to its overly complex delayed-blowback design. This design used a system of levers within the breech block to release a firing pin that rusted easily in the humid jungle climate. This problem was exacerbated by the bolt delay recess in the receiver that could accumulate dirt or fouling from gunpowder, preventing the bolt from seating properly; if the bolt was not seated in its recess, the trigger disconnector prevented firing. In addition, the magazine was a staggered-column, single-cartridge feed design, and slight damage to the feed lips or debris in the magazine would render the magazine unusable. (A partial solution to the magazine problem was the later introduction of a single column magazine which reduced the capacity from 20 to 12 rounds.)
The Reising soon earned a dismal reputation for reliability under Guadalcanal combat conditions. Reportedly, many Marines would discard the weapon upon finding just about anything else, and one NCO reportedly "decommissioned" his Reising by breaking the stock over the head of a particularly insolent "brig rat". Lt. Col. Merritt Edson, commanding officer of a Marine Raider battalion, ordered all Reising submachine guns issued to his unit to be dumped unceremoniously into a river, so that his men might draw better weapons. The M1 carbine, as it became available, was often chosen over both the Reising and the Thompson in the wet jungle conditions, with the built-in oiling pads in the receiver of the Thompson M1928 and M1928A1 being a liability.
Read more about this topic: M50 Reising