Credit: Bas Martens

The MP38 hinged muzzle cap serves two primary functions. First, it prevents debris from entering the barrel, ensuring it remains clean under all conditions to avoid malfunctions or more serious issues. Second, when opened, the cap acts as a guide rod for cleaning tools, such as the brush and chain from the RG34 cleaning kit.

Muzzle caps were manufactured for a wide range of rifles, machine guns, and submachine guns. The earliest mention of a muzzle cap for the MP38 appears in its original 1938 manual, "Beschreibung der Maschinenpistole 38 (M.P.38)." The accompanying photo showcases several early MP38 accessories, including a prototype muzzle cap. Its design differs noticeably from the later mass-produced version.

Mündungsschöner / Muzzle cap

b. Muzzle Protector.
(Table II, Image 2b)

The muzzle protector serves not only to protect the muzzle and the bore from contamination but also as a guide for the chain of the cleaning device, so that the muzzle does not become prematurely widened.

Therefore, it must be attached to the muzzle during cleaning.

It is locked onto the front sight guard under light pressure and a clockwise turn onto a notch.

Versions

There were essentially three versions of the muzzle protector, or muzzle cap, for the MP38/40/41 series, not taking into account the proto type version in the previous photo:

The first version was the metal muzzle protector produced specifically for the MP38. This design was based on the metal muzzle cap made for the K98 rifle, though the caps are not interchangeable. The MP38 featured an L-shaped notch attached to the front sight protector, allowing the metal muzzle cap to be secured. This design ensured that the entire muzzle nut was covered by the cap. The muzzle cap itself included a metal lid that could be opened or closed. The lid was primarily intended for cleaning purposes. The inner diameter of the muzzle protector was slightly smaller than the 9mm caliber—approximately 7.8mm. This smaller opening acted as a guide for the cleaning chain, preventing damage to the muzzle. The muzzle cap was never intended for firing through. When firing ammunition with a sharp projectile, the entire muzzle protector had to be removed. Failure to do so could result in serious accidents.

Credit: Bas Martens

The early MP40s featured the same L-shaped notches on the front sight. Based on serial numbers, it appears that Steyr ceased production of the L-shaped notch on the MP40 by 1940. So far, I have not encountered any BNZ-coded MP40s with this feature; only 660-coded MP40s include them. Haenel and Erma, however, continued to produce MP38s and MP40s with this feature well into 1941.

The metal muzzle cap was an overly complex and expensive accessory. Its small components did not always function reliably. In addition to the risk of accidents mentioned earlier, the cap also had a tendency to freeze in winter conditions, making it difficult for soldiers to open or remove it when needed.

The metal muzzle cap, or "Mündungsschoner", shown on this page features a Waffenamt stamp marked "WaA101". Above this Waffenamt code, there is another small commercial logo. It displays two small capital B's enclosed by a large C. This logo represents the following company:

C. Bettenmüller & Cie., GmbH., Metallwarenfabrik, Bretten/Baden, Germany (Secret code: "an")

As from October 1941 the hinged muzzle cap were marked only with the "an" code and the Waffenamt stamp—or had no markings at all.

The second version is the rubber muzzle cap. It was introduced alongside the muzzle cap for the MG34 in the Heeres-Verordnungsblatt on June 25, 1940. Below is the official announcement along with its translation:

679. Muzzle Cap for M.G. 34 and M.P.

To prevent the entry of dust, water, or other foreign objects into the barrel of the M.G. 34 or the M.P., a muzzle cap is introduced.

Designation: a) Muzzle Cap M.G. 34
b) Muzzle Cap M.P.

Distribution:

Material Classification Number: a) 2
b) 1

Request Code a) J 67 375
b) J 53 007

The muzzle cap M.G. 34 is available for each M.G. 34, and the muzzle cap M.P. is available for each M.P. 38 and 40. However, for the M.P. 38, only if the muzzle cone is not present.

The following are supplied:
The muzzle cap M.G. 34:

2 in the maintenance box 34 (Attachment to A.M. [Army Manual] J 325 and J 327)
25 in the supplementary box for M.G. 34 (Attachment to A.M. [Army Manual] J 339)

(Changes in attachments should be made in pencil.)

The muzzle cap M.P.:

1 in the accessories for A.M. [Army Manual] J 15
10 in the standard reserve box, attachment to A.M. [Army Manual] J 17

(The attachments J 15 and J 17 will be published later in a revised edition.)

The MP40 rubber muzzle cap was similar to the one used on the K98 but slightly larger to fit the 9mm muzzle nut. Its main advantage was that, in an emergency, it allowed the soldier to fire through the rubber cap. Each soldier equipped with an MP40 received four of these caps.

With the introduction of the rubber cap, factories also switched to a redesigned muzzle nut. The earlier muzzle nut lacked a machined groove, as it was not required for the older hinged metal muzzle cap. However, all MP40s produced after 1941 featured the new muzzle nut with a groove.

Original rubber muzzle caps are now quite rare since they were considered expendable. Occasionally, they are found as ground-dug relics. However, many reproductions are currently being sold as originals.

The rubber MP40 cap was also used on early MP44 models. Later MP44s, or StG44s, no longer featured a muzzle nut.

Originally, the rubber muzzle cap was flexible and elastic. Today, due to age, it often needs to be heated before it can be fitted onto the muzzle.

The third version emerged as a response to shortages in the supply of rubber muzzle caps. Soldiers were advised in an issue of "Von der Front für die Front" to create a makeshift cap using oil-treated cardboard, which could be placed over the muzzle.

Below is a copy and its translation of the notice published in "Von der Front für die Front" on April 20, 1944.

Muzzle Protector for the Submachine Gun
Made from a Piece of Cardboard

Muzzle protectors for the MP are often unavailable. However, you can easily make one yourself. Cut the following shape from a piece of cardboard:

(Diagram showing the shape)

The tab is folded inward; it serves to make it easier to remove the cardboard piece once it has been inserted into the protruding edge of the muzzle nut. The cardboard piece must fit tightly so that it does not fall out. The size can be determined by pressing the muzzle nut onto the cardboard and marking its outline.

In wet weather, the cardboard piece should be treated with waterproofing agent or slightly oiled.

Gefr. Erich Faber
Field Post Number 07 666 F

Reproduction

Below are photos of a reproduction hinged muzzle cap. These were produced on behalf of a French militaria dealer, likely in the Khyber Pass region of Pakistan. They are relatively easy to identify. If you're unsure about the authenticity of your muzzle cap, feel free to send me an email. Apart from the obvious differences there is also the price at which they are being offered. This is significantly lower than typical collector market prices for originals, which should raise concerns about their originality.

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Die Maschinenpistole MP38, MP40, MP41

Die Maschinenpistole MP38, MP40, MP41

Mündungsschöner / Muzzle cap

Versions

Reproduction

Support and Contributions to MP38, MP40, and MP41 Research