SIG MKMS
Encyclopedia
The SIG MKMS was sub-machine gun designed by Schweizerische Industrie Gesellschaft
Schweizerische Industrie Gesellschaft
Schweizerische Industrie Gesellschaft , or SIG, is the former name of SIG Holding AG, a Swiss company that has been active in various businesses during its more than 150 years of operation. Since the year 2000 the Society has undergone strategic refocus, concentrating on its core compentence in...

 (SIG) company in Neuhausen
Neuhausen
Neuhausen may refer to:*Neuhausen am Rheinfall, a town in the canton of Schaffhausen, Switzerland*Neuhausen auf den Fildern, a municipality in Baden-Württemberg, Germany*Neuhausen , a municipality in Baden-Württemberg, Germany...

 during the early 1930s and was first introduced in 1933. It was designed for the military and to increase firepower it had a larger capacity magazine as well as a longer barrel, one that would be more common on an assault rifle. Only 1,228 of these guns were produced.

Design

The SIG MKMS made use of an ingenious delayed blowback action which kept the cartridge within the chamber long enough for bullet to leave long barrel thus prevented a bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...

s colliding in the barrel. The delayed blowback action was made up of a two-part bolt which was designed by Gottard End. It was also the first ever personal weapon to have a folding magazine so the longer than usual magazine could be stored horizontally within the wooden stock. This made transportation during non-combat movement easy and much less effortless compared to some guns without folding magazines, yet when trouble did arise, a simple catch system would release the magazine allowing normal firing to commence.

Delayed Blowback Action

The locked-breach blowback system mirrored that of John Pedersen
John Pedersen
John Douglas Pedersen was a prolific arms designer who worked for Remington Arms, and later for the United States Government. Famed gun designer John Moses Browning told Maj. Gen. Julian S. Hatcher of U.S...

's Remington Model 51
Remington 51
The Remington 51 is a small pocket pistol designed by John Pedersen and manufactured by Remington Arms in the early 20th century for the American civilian market...

 only with a locking recess above rather than below the bolt. The longer barrel of the MKMS required either a bolt of greater mass or a locking system. When the firearm is in battery
Out-of-battery
Out-of-battery refers to the status of a weapon before the action has returned to the normal firing position. The term originates from artillery, referring to a gun that fires before it has been pulled back into its firing position in a gun battery....

, the breech block rests slightly forward of the locking shoulder in the frame. When the cartridge is fired, the breech block and bolt carrier move together a short distance rearward powered by the energy of the cartridge as in a standard blowback system. When the breech block contacts the locking shoulder, it stops, locking the breech. The bolt carrier continues rearward with the momentum it acquired in the initial phase. This delay allows chamber pressure to drop to safe levels while the breech is locked and the cartridge slightly extracted. Once the bullet leaves the barrel and pressure drops, the continuing motion of the bolt carrier cams the breech block from its locking recess, continuing the operating cycle.

Other Features

There was no fire selector switch for single or automatic fire. This was gauged by the force of pull on the trigger. A short pull was for single shot and a long pull was for automatic fire. This was also one of the first sub-machine guns that had an integral dust cover on the magazine housing.

Variants

There were 3 variants of the MKMS. There was the shortened barreled MKPS which still used the overly complicated two-part delayed blowback action. This was designed for the police market. In 1935, SIG then created the MKMO and the MKPO. The MKMO had the long barrel of the MKMS but had a more conventional single-part blowback action while the MKPO had the shortened barrel as well as the single-part bolt blowback action. Both also fired from open bolt manual safety which was located on the left side of receiver.

Specifications of MKPS
Category MKPS
Calibre 7.63x25 Mauser, 9x19 Luger
Empty Weight 3.6 kg
Length 820 mm
Barrel Length 300 mm
Rate of Fire 900 rounds per minute
Magazine capacity 30 rounds
Effective range 200 metres


Both MKMS and MKPS submachine guns were somewhat complicated and made to extremely high standards, so the price was high and sales were low and thus production was stopped in 1941.

Sighting Flaws

The sights for both the MKMS and MKPS were both fully manually adjustable but could be calibrated from 100 metres to an optimistic 1000 metres. This led to much confusion with accuracy often found wanting in young soldiers who couldn't operate the sights properly.
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