MP34 Maschinen Pistole in 45ACP!

By Vince Oliva

Every so often we find a vintage weapon in an unusual, odd ball caliber. Not saying that the 45 ACP is an odd caliber, we all know the 45 ACP is the original old war/horse. In this scenario, we have a classic, German designed, MP34 chambered for a 45 ACP cartridge instead of the standard European 9mm round. First let me pass on a little history of the MP34(ö)

Cultured Austria did very little in the field of weapons development prior to WWII.They did develop one submachine gun which attained fairly wide usage before and during WWII. The MP34(ö) is commonly known as the Steyr Solothurn. This weapon is a product of German design worked out at Waffenfabrik Solothurn A.G. of Solothurn, Switzerland. Solothurn A.G. was a Swiss industrial company owned by Rheinmettal A.G. of Germany. Herr Louise Stange of the Rheinmettal Company of Dusseldorf originally designed the MP34 in 1924. Under the terms of the Versaillies Treaty, Rheinmettal was forbidden to develop or manufacture military arms. To circumvent this restriction, Rhienmettal A.G. acquired a Swiss company called Solothurn AG in 1929 and used this company to produce the prototypes and accomplished development engineering. But the Solothurn AG was not equipped to produce in quantity, so Rheinmettal now took a controlling interest in the Waffenfabrik Steyr and arranged for the weapon to be put in production as the “Steyr-Solothurn” sub-machine gun. It was widely sold throughout the world in a variety of calibers.

The Austrian MP34 was “kindly adopted” by the Germans when they took over Austria in 1938 and was called by the Germans MP34(ö) - Maschinen Pistole 34 Õsterreich-, (Õsterreich meaning Austrian). The weapon was widely used by German police and rear area units. The weapon in various modifications and caliber’s was offered commercially and obviously the 45ACP for export only. Chile, El Salvador, Bolivia, and Uruguay were some of the known importers. The Japanese had a few extremely limited quantities in 7.63 Mauser. The commercial designation for the weapon is SI-100. It is probable that all the MP34s(ö) used by Austria were made by Steyr, as from 1930 on, the gun was known as the Steyr Solothurn.

The MP34 as used by the Austrian Army and was chambered for the 9mm Mauser cartridge. It was also issued to the Austrian police in 9mm Steyr, both calibers were found in German service or police units. When Austria was incorporated into the Third Reich the weapon was taken into German Army service as the MP34(ö) (ö for Õsterreich) and extensively used. Then re-chambered for the more common 9mm Parabellum round.

Note: do not confuse the Bergmann MP34 with the MP34(ö). The MP34 is the only subgun designed by Bergmann. Manufactured by Carl Walter Waffenfabrik, Zella-Mehlis, Junker & Ruh AG, Karlsruhe.

The Bergmann MP34 has a double trigger of peculiar form; pulling the front trigger gave single shots, but further pressure caused it to bear on the secondary trigger to give automatic fire. Whereas the MP34(ö) has the selector on the left side of the stock and also the Bergmann MP34 has a built in compensator at the muzzle and a safety slot cut into the top receiver cover for the bolt to be safely locked back.

Unusual Features of MP34(ö)

The weapon is typical of the period in which it was made of heavy forging. The only unusual feature is the Magazine loader in which is machined into the magazine housing. The magazine is inserted into the underside of the magazine housing and is then loaded with ten round chargers-stripper clips through the opening in the top of the magazine housing.
Note: On the 45 ACP version the magazine housing is of a solid piece of stock and the Magazines are loaded in the conventional method.

Characteristics of Austrian MP34(ö) Submachine gun

Caliber: 9mm Mauser (Army Model)
System of Operation: Blowback
Weight loaded: 9.87 lbs.
Barrel length: 7.80 in.
Feed mechanism: 32 round detachable, staggered box magazine.
Sights: Front: Barney corn
Rear: Tangent with “V” notch graduated from 50-500 meters in 50-meter increments.
Muzzle velocity: 1300 fps (for 9mm Mauser)
Cyclic rate:500 rounds per minute.
Bayonet: - utilized the Austrian M95

Solothurn S1-100 Civilian version

The Solothurn S1-100 in Austrian guise as the MP34(ö) or Steyn-Solothurn

Length:33.5 in
Weight:8lb 8oz
Barrel:7.75in long, 6 grooves, right hand twist
Feed System: 32 round detachable box magazine
System of operation: Blowback, selective fire
Cyclic rate: 500rpm
Manufactures: Waffenfabrik Solothurn AG, Solothurn, Switzerland, Waffenfabrik Steyr, Steyr, Austria

The S1-100 is generally considered to be the ‘Rolls-Royce’ of sub-machine guns, made of the finest available materials and finished to the highest possible standard. Its mechanism is quite simple, the usual bolt having its return spring housed in the wooded buttstock, and the firing pin being separate. It fires from an open bolt in the usual blowback mode. One of the most unusual features is the incorporation of a magazine loading device in the magazine housing. The first specimens of this weapon were generally made in 7.63mm Mauser caliber or 9mm Steyr, and ammunition of these types was always supplied in pre-packed 10-round chargers for use in the pistols. So that these chargers could be used for loading the sub-machine gun magazines, the magazine housing has a slot in top and bottom; the empty magazine could be withdrawn from its housing and slipped into the bottom slot. Chargers of cartridges were then inserted into guides in the top slot and the rounds stripped down into the magazine.

MP34 in 45 ACP

I had acquired this weapon from Ron Darnell of Darnell’s Gun Works & Range of Bloomington, IL. Ron had set up a table at the Spring 2000 Knob Creek shoot and this is where I spotted this beauty. Ron was cleaning house one day “actually he was building a new one” and decided to clean up this treasure that he acquired many years before from an estate sale. From what information that Ron passed on to me is that a bunch of these MP34s were imported into the U.S. by ARMEX in the early 1980s from South and Central America.

The weapon was in fair condition and missing the very rare 45ACP Magazine. Mike Grady; is the Gunsmith for Darnells Gun Works, Mike and Ron got to looking closely at the gun and realized that other than the bolt, barrel (9mm), top cover and magazine housing everything was essentially the same as the standard Steyr 9mm. The 45 ACP barrel threads and physical dimensions were the same for the standard 9mm barrel, His biggest obstacle was to make a Magazine adapter to fit in the Magazine housing for the standard 9mm mags. No problem for Mike, as the master that he is, Mike machined out an adapter in the precise internal dimensions of the magazine well. Mike also hand polished a re-blue to the steel better than the Old World Masters. Now to find the MP34 45ACP magazine, well a few phone calls to many of the industries best and good old Bob Landies came up with one.

Another factor that I can not verify is the total number of models made in 45 ACP. Ron Darnell seems to remember reading some where that about 500 hundred were made but again not verified.

Shooting this firearm is pure pleasure; it lifts and fits naturally to my shoulder and the sight alignment seems natural. But again shooting the same gun in different calibers is night and day. The 9mm is smooth and very, very controllable. Whereas the 45ACP is also smooth and controllable but you know you are shooting a 45 and the shooter has to master the extra energy of the 45.

One discrepancy that I found between previous published information and my measurements are the overall lengths of the barrels. My measurements on the 45 ACP barrel and my 9mm parts kit barrel are identical at 8.12 inches. Other published listings were of 7.8 and 7.75 inches.

Magazines in 45 ACP are as rare as hens teeth. I have only one original 20 round Magazine. My research did not afford me any information on this subject. I do not know if they made 10,15 or 30 round 45ACP mags for this gun. I have a modified 30 round Thompson mag that has been cut and reshaped that works quite well and I have been looking at the possibility of modifying Grease gun mags. You fellow shooters know nothing works best other than the originals.

Now we have a firearm that shoots both calibers that takes less than 2 minutes to change.

From 45 ACP to 9mm in steps: Naturally reverse order to change.

1. Open top cover and remove (one screw).
2. Pull back and lift out 45 ACP Bolt
3. Unscrew 45 ACP barrel
4. Screw in 9mm barrel - no specific torque, just snug with adjustable wrench.
5. Install 9mm Bolt
6. Install 9mm top cover
7. Install 9mm magazine well adapter

Specifications of this Featured MP34 in 45 ACP

Weight: 9.75 lbs.
Weight: - Fully loaded with 22 round Mag. 230gr. Bullets - 11 lbs.
Barrel length - 8.125 inches
Bolt weight - without guide rod - 2.25 lbs.
Bolt length - without guide rod - 7.13 inches
Bolt length - with guide rod - 13.88 inches
Feed mechanism: 20 round detachable, staggered box magazine.
Sights: Front: Barney corn.
Rear: Tangent with “V” notch graduated from 30-110 meters in 10-meter increments.
Cyclic Rate: Unknown at this time. I didn’t have the proper electronic measuring devices at the time of this writing but on firing the 45ACP model it was very audible to myself and by other firearm enthusiasts that the cycling rate was much faster. This was due to the nature of physics - basically looking at the physical dimensions of the 45 Bolt - it is larger and longer than the 9mm bolt, thus a shorter stroke or travel distance.

*The Receiver Top Bolt cover incorporates the safety bolt slot cut into the side. Whereas the 9mm has the push button safety on the top receiver cover for the bolt. *The bolt does not have the safety slot cut like the 9mm

Specification of this Featured 9mm parts kit incorporated into the MP34 45ACP Receiver.

Weight: 9.125 lbs.
Weight: - Fully loaded with 32 round Mag. 115 gr. Bullets - 10.5 lbs.
Barrel length - 8.125 inches
Bolt weight - 1.75 lbs.
Bolt length - without guide rod - 5.75 inches
Bolt length - with guide rod - 12.5 inches
Feed mechanism: 32 round detachable, staggered box magazine.

Incorporates push button top receiver cover safety. Does not incorporate safety bolt slot cut, but incorporates push button lock down
Sights: Front: Barney corn
Rear: Tangent with “V” notch graduated from 50-500 meters in 50-meter increments.

Another feature is the ability for bayonet attachment. The Austrians did not want to re-invent the wheel so they incorporated the Steyr 1895 rifle bayonet, also known as the M95 bayonet to fit on the MP34. I found that the M1934 (modified M1904 bayonet) Solothurn SMG bayonet made by Simson & Co. of Suhl for Portugal fits perfect. The M1934 bayonet is one inch longer than the M95 Steyr bayonet. Neither of these Bayonets will fit the 45ACP model because the muzzle diameter of the 45ACP barrel is .04 inches wider than the 9mm barrel. I filed and sanded the inside barrel port of the M95 bayonet and it fits perfect on the 45 barrel. I do not believe a specific bayonet was made for the 45ACP model and the modification I performed were probably the same.

Note: Some technical data specifications are from the book: Small Arms of the world by Smith and Smith (Stackpole books) 1969

This article first appeared in Small Arms Review V4N7 (April 2001)
and was posted online on June 27, 2014


04-13-2016 12:26 PM

incorrect illustrations

is it only me, am I the only one getting illustrations and captions not matching

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