Will Swedish K M45 magazines fit and work in a S&W M76?

[daninnm]

I have some of both but concerned about fit and use?  Anyone done this swap?  Can M45s be 'adjusted', machined, or filed on to work in S&W M76?

Edited August 8, 2022 by daninnm
spelling

[Dean]

No

[Got Uzi]

They will if you modify them but it can be a bit of a pain. Then again cost of M36 mags vs S&W mags it’s worth it. 

[Navgunner]

@Got Uzi nailed it. Yes, my personal experience says that you can “fit” them to work. Last I remember, UZI Talk.com had a good writeup on their board explaining the process. 

[Frank I]

 

From the Smith & Wesson Model 76  book

see last paragraph

Magazines

 

The thirty-six round magazines designed for the S&W 76 submachine gun are very similar to those made for the Suomi and Swedish-K. The magazines were of the proven wedge-shaped, double-stack, double-feed design and very reliable. Original S&W M76 factory magazines were finished with a medium to light gray-green parkerizing. The magazines can be identified by markings on the floorplate, and a vertical groove embossed on each side of the magazine’s body. Original magazines for the Model 76 have far exceeded their original MSRP of $13.35; today the cost of an original magazine will often exceed $100.00 due to their limited numbers. The floorplates of original S&W factory magazine are marked 9MM or 9MM CTG. There are three different style floorplates found on the magazines. The early production floorplates have a short tab to help secure them to the magazine body. The tab can also be used as a screwdriver to disassemble the weapon. A potentially serious problem was revealed when it was discovered that a magazine could accidentally be inserted into the magazine well upside-down, and it would lock in place. The problem could prove fatal in a high-stress police or military situation. The problem was addressed, and quickly solved, by designing a floorplate with a longer front tab, which would block the magazine’s insertion into the magazine well. The newer style floorplates with the longer tab have the 9MM CTG. marking at the front of the floorplate facing forward. The older short-tab style had the same markings, but at the back of the floorplate facing rearward.

 Aftermarket   Magazines  

Magazines that are very similar to those made by the Smith & Wesson factory were made for the MK 760 and 76A1submachine gun clones. Although very similar to the original magazines, they can be identified by their unmarked floorplates. In addition, the cartridge marking numbers on the back of the magazine body are a different font.

The cartridge sight holes in original Smith &Wesson magazines are slightly larger at approximately .140-inch versus the hole size in the MK 760  magazine, which is approximately .120-inch 

Note: it is possible that the floorplates could be installed upside-down in an original S&W factory magazine. In such a case the floorplate markings would not  be visible.

Another small detail difference between original and aftermarket magazines is the groove that is impressed into the side of the magazine body. On original Smith and Wesson magazines, the groove has a V shape, while on the aftermarket magazines the groove has more of a U shape. The magazine followers are also different.

Original followers are a sheet metal stamping; aftermarket followers have been observed made of plastic or a metal casting.

Tolerances in the magazine housings on some Model 76 copies have caused magazine fit and feeding problems by being over or under sized. This problem often results in the magazine being individually fitted to a particular weapon that may not fit or function in another similar gun. The magazine fit is not a problem in original manufacture S&W Model 76 submachine guns using original S&W magazines.     

A few years ago, a large number of Finnish-made 36-round magazines for the Suomi submachine guns were imported. Many were in new condition. The Finnish magazines are the same style that Smith & Wesson used for their Model 76. The Suomi magazines will fit and function in an S&W Model 76 by removing a slight amount of metal from the surface of the front plate. The Suomi magazines have a blued finish, but many owners like to have their converted magazine parkerized to match the finish on the original magazines.

 

 

Edited August 9, 2022 by Frank Iannamico

[Navgunner]

6 minutes ago, Frank Iannamico said:

 

From the Smith & Wesson Model 76  book

see last paragraph

Magazines

 

The thirty-six round magazines designed for the S&W 76 submachine gun are very similar to those made for the Suomi and Swedish-K. The magazines were of the proven wedge-shaped, double-stack, double-feed design and very reliable. Original S&W M76 factory magazines were finished with a medium to light gray-green parkerizing. The magazines can be identified by markings on the floorplate, and a vertical groove embossed on each side of the magazine’s body. Original magazines for the Model 76 have far exceeded their original MSRP of $13.35; today the cost of an original magazine will often exceed $100.00 due to their limited numbers. The floorplates of original S&W factory magazine are marked 9MM or 9MM CTG. There are three different style floorplates found on the magazines. The early production floorplates have a short tab to help secure them to the magazine body. The tab can also be used as a screwdriver to disassemble the weapon. A potentially serious problem was revealed when it was discovered that a magazine could accidentally be inserted into the magazine well upside-down, and it would lock in place. The problem could prove fatal in a high-stress police or military situation. The problem was addressed, and quickly solved, by designing a floorplate with a longer front tab, which would block the magazine’s insertion into the magazine well. The newer style floorplates with the longer tab have the 9MM CTG. marking at the front of the floorplate facing forward. The older short-tab style had the same markings, but at the back of the floorplate facing rearward.

 Aftermarket   Magazines  

Magazines that are very similar to those made by the Smith & Wesson factory were made for the MK 760 and 76A1submachine gun clones. Although very similar to the original magazines, they can be identified by their unmarked floorplates. In addition, the cartridge marking numbers on the back of the magazine body are a different font.

The cartridge sight holes in original Smith &Wesson magazines are slightly larger at approximately .140-inch versus the hole size in the MK 760  magazine, which is approximately .120-inch 

Note: it is possible that the floorplates could be installed upside-down in an original S&W factory magazine. In such a case the floorplate markings would not  be visible.

Another small detail difference between original and aftermarket magazines is the groove that is impressed into the side of the magazine body. On original Smith and Wesson magazines, the groove has a V shape, while on the aftermarket magazines the groove has more of a U shape. The magazine followers are also different.

Original followers are a sheet metal stamping; aftermarket followers have been observed made of plastic or a metal casting.

Tolerances in the magazine housings on some Model 76 copies have caused magazine fit and feeding problems by being over or under sized. This problem often results in the magazine being individually fitted to a particular weapon that may not fit or function in another similar gun. The magazine fit is not a problem in original manufacture S&W Model 76 submachine guns using original S&W magazines.     

A few years ago, a large number of Finnish-made 36-round magazines for the Suomi submachine guns were imported. Many were in new condition. The Finnish magazines are the same style that Smith & Wesson used for their Model 76. The Suomi magazines will fit and function in an S&W Model 76 by removing a slight amount of metal from the surface of the front plate. The Suomi magazines have a blued finish, but many owners like to have their converted magazine parkerized to match the finish on the original magazines.

 

 

Well done!

[Bwana]

Frank sums it up nicely (great book too!).  It is a VERY EASY task to get the Suomi stick mags to work in a MK760 or SW76. Just need a little patience and a dremel with a sander wheel. Take off just a little metal from the forward edge of the mag (muzzle end) that engages the mag catch. There should be a small raised rectangle of metal that you are working.  Try to lock the mag in place.  Repeat until it locks and releases consistently. Maybe 2-3 minutes per mag.  A little longer if you're very meticulous.

The last MK760 that I had come through actually worked with unmodified Suomi stick mags. I have no idea if anyone modified it, but I recall that the parkerized MK mags that came with the gun also plugged into the Swed K.  I wish that I had checked more closely to see if the catch had been modified. It seems like it wouldn't take much to bend in the mag catch just enough for the stick mags to lock into place. Not recommended for a SW76 but possibly worth it with a MK760.

Another quick note from the book excerpt - I have found about 4 factory SW76 mags that had the baseplate (with all "CTG..." markings) installed upside-down.  Just by flipping the baseplate the mag value jumped well over $100 (LOL)...

Good luck!