The designers of the MP38 and MP40 specifically engineered the barrels of these weapons to accommodate a blank firing device. This is the primary reason why both models were equipped with a removable muzzle nut that could be unscrewed from the barrel. At the time, there were no developments or considerations for sound suppressors or similar attachments. The inclusion of the device in technical and administrative manuals, as well as on instructional posters, suggests that the intention was to produce and distribute the device on a large scale, much like other standard accessories such as pouches, loaders, and magazine brushes.

Interestingly, the Wehrmacht never made a serious effort to develop a dedicated blank cartridge during World War II. Some limited experiments were conducted during the 1920s and 1930s. However, in 1937 and early 1938, the Heereswaffenamt initially planned for the new MP38 to support a blank firing device. This requirement indicates an intention to develop such cartridges, but the idea appears to have been quickly abandoned. Production of the device was likely halted after only a few prototypes or possibly a small production batch.

The Platzpatronengerät (blank firing device) was a prime example of German over-engineering, a characteristic often seen in their weapon designs. Another comparable example is the hinged muzzle cap.

In general, blank firing devices for blowback and gas-operated firearms are relatively simple in construction. These weapons rely on the high pressure generated by the ignition of propellant to push the bolt rearward, cycling the next round. When firing blank cartridges, no bullet seals the barrel, and the gases escape through the muzzle without building sufficient pressure to rechamber the next cartridge.

A basic blank firing device typically consists of a metal cap that screws onto the barrel. These adapters regulate the amount of gas retained, ensuring sufficient pressure to cycle the weapon. Advanced devices may allow for adjustable gas pressure, providing finer control over the operation.

One drawback of using blank firing devices, particularly in gas-operated firearms, is the accumulation of residue in the barrel. With no projectile to expel, most of the residue remains in the system, causing rapid fouling. This necessitates thorough cleaning after use to prevent stoppages or damage.

The specific blank firing device designed for the MP38 and MP40 was somewhat more complex. It consisted of a cap and an internal tube that could be inserted into the barrel. The cap featured two screws: one to regulate gas pressure and another to secure the adjustment screw in place. After firing a blank cartridge, the gases were forced through the internal tube and exited the cap through two exhaust holes, controlled by the gas pressure screw.

The text slightly differs from the text in the D167/1. What is more interesting is that Steyr is being mentioned. Steyr was the main manufacturer of the MP40 from 1940 until 1944. This is confirmed with the Waffenamt code WaA623.

One would expect that Steyr would be the manufacturer of this device but on the main body of the device an unknow logo appears that definitely is not a logo from Steyr. The logo and letters are not clearly visible as the main housing is painted white. The logo seems to have a shape of an octagon and some unclear letter are depicted within the octagon. An “F” or “Z”??

Commercial logos were incidentally used until 1940. After this year generally the secret armament codes were used on military equipment. This suggest this specific blank firing device was probably used on an MP38.