Simon Garner for original article and scans, "Der Windhund" (AFRA's newsletter) for permission to reprint, P. Dalby.
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The 9mm Model 38, Model 40 and 41 Submachine Gun (MP38,40 & 41)
The MP38 was the first submachine gun developed for the German Army since the MP18 of World War I. Although the design has been credited to Schmeisser in many publications, it was probably designed by Erma as first production was carried out on that plant. The telescoping, multi-piece recoil spring and firing pin assembly were developed from those used by the Erma sub machine gun. The MP38 was made from 1938 to 1940 at the Erma plant. The plastic receiver housing and aluminium frame and folding stock design of the weapon had considerable influence on later submachine guns. The receiver of the MP38 is made from steel tubing.
Fig. 1 - The Mp38
The MP38 had one serious deficiency - which is shared by most SMGs. It was not completely safe to handle. The only safety, a cut out in the receiver into which the bolt handle locked when the gun was cocked, did not allow the gun to be carried safely with the bolt forward and a loaded magazine in the gun. If the gun received a sever jolt, such as falling on its breech end, the bolt could bounce back far enough for it to pick up a round from the magazine and fire. The MP38 was modified to remedy this defect by the fitting of a two-piece bolt handle and the cutting of a slot above the front of the bolt receiver track to lock the bolt into the forward position. This modification was called the MP38/40.
The MP38 was somewhat expensive to manufacture and the weapon was re-engineered to cut down the use of expensive tooling. The weapon produced as a result was called the MP40, which differs from the MP38 in the following: new ejector, magazine release assembly, receiver (ribbing eliminated), grip frame of the MP38 is aluminium whilst he MP40 is formed, and the stamped middle tube of the recoil spring assembly is drawn and pinched on the MP40. There are numerous other minor differences. The MP40 was made in much larger quantities than the MP38 and was manufactured by Steyr, Haenel and Erma with the assistance of a number of subcontractors. Over 1,000,000 MP40s were made from 1940 to 1944.
There were several modifications to the MP40. The most common modification had a stamped, ribbed magazine housing and two piece bolt handle. This weapon, which was called the MP40/I, was far more common than the MP40 itself. A rarer modification was the MP40/II, which was fitted with a magazine housing to accommodate two magazines. The magazines were held in a sliding housing arranged to allow each magazine to feed in turn.
The MP41 was developed at Haenel by Schmeisser. It was made in very limited numbers and was not used by the German Army or Police. It may have been made for export. MP41 had the receiver and barrel assembly along with the bolt assembly of the MP40 but the stock and trigger mechanism of the MP28II.
Loading and Firing the MP38
Six spare magazines and a loader are issued in a web haversack with each one of these guns. The loader is a simple lever device with an attached housing into which the magazine is inserted. Snapping a cartridge into the top of the housing and pushing down on the lever loads the individual cartridge into the magazine. This motion is repeated until the magazine is filled. If no loader is available, the rounds may be loaded by the normal procedure for loading automatic pistol magazines. Leverage for inserting the last few rounds may be exerted by both thumbs one the round has been seated.
Fig. 3 - Loading the Mp38/40
How the MP38/40 Works
The loaded magazine inserted from below is held securely in place by the magazine lock. The firing pin is attached to the forward end of the telescoping housing. It passes through the hole in the centre of the bolt, while the abutment behind it lodges into the head of the bolt recess. As the bolt is drawn back by its handle, or forced back by the functioning cartridge, it telescopes the three-piece recoil spring housing (which carries the firing pin) and compresses the recoil spring inside its telescope. The rear of the recoil spring rests against the inside of the rounded buffer end of the frame, which is securely locked to the receiver. When the bolt is in the fully cocked position the sear locks into the bottom of the bolt and connects with the trigger. Pressing the trigger depresses the sear and permits the bolt to run forward under the influence of the recoil spring acting through the telescopic section to force the bolt forward.
As the feed ribs on the bottom of the bolt strip the top round from the magazine and push it into the chamber, the face of the extractor set in the bolt blocks the base of the cartridge. When the cartridge is fully seated, the further forward movement of the bolt pushes the heavy extractor to snap it into the extracting groove. At the same time the bolt face strikes against the base of the cartridge. The firing pin, a separate unit from the bolt is under the pressure of the recoil spring and functions in the same manner as a fixed firing pin. It protrudes at all times. This pin now strikes the primer in the cartridge and discharges it. During the rearward action, the extractor hook withdraws the spent cartridge, carrying it back until it strikes against the ejector and is ejected. This cycle of operation continues as long as the trigger is held back and there are rounds in the magazine.
MP38 (MP40 marked with * where data differs)
Calibre 9mm Parabellum
Operation Full auto only Gas Blowback
Stock out 32.8"
Stock in 24.8"
Barrel Length 9.9in
Feed 32 rd detachable staggered box magazine
Front Hooded barleycorn
Rear Notched flip over leaf
Weight 9.5lbs * 8.87lbs
Cyclic rate 500 rpm
Muzzle Velocity 1300fps approx
Fig. 4 - Technical Data