Swiss 12.7x64B MKS

I just stumbled across a Swiss 1970 sniper rifle development named “MKS” which fired a 12.7x64B cartridge.

Is there more or better info on the subject?
Images of the cartridge(s)?



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I do not know what the Russian source says. The gun is shown under the heading “Schallarme Waffe” (low noise weapon), designed by Waffenfabrik Bern, in the book Automatwaffen II by Reinhart/am Rhyn (Stocker-Schmid 1983), p. 132-133. “MKS” is not mentioned.
The book has no better photo of the cartridge and lacks any ballistic data beyond the obvious subsonic muzzle velocity. Total length 1000 mm, including silencer; barrel Length 460 mm, maximum gas pressure 1050 bar. AP and Incendiary bullets were used.
Comparison with a 7.5x55 GP11 shown alongside the above cartridge let me estimate case length as 61 mm (not including the driving-band like artefact in front of the case mouth).
Hope this helps.
It is interesting that Ilya Shaydurov in the last issue of Visier presents a Russian 12.7x55 subsonic rifle as if that Swiss subsonic 12.7 mm had never existed.

Jochem, thank you for rounding up what is known so far!
Maybe more people can contribute some bits and pieces?
Is known if Woodin Lab has one of these?

I also wonder if people know about the Finnish side of the 12.7x55, except for a handfull of people everybody calls it “Russian only”.


Here is a fired case with correct projectile.




Paul, thanks a lot!
I guess this is it now!

Is this case for the same gun ?

No, this is a Swiss made 13x64B MG131.
And an outstanding item!!!

Thank Alex !!!

Yes - a few years ago I exchanged correspondence with a Finnish designer concerning their 12.7 x 55 (based on the .338 Lapua Mag case). The Russian round was a copy of that, as I understand it. I put an article about this in the ECRA Bulletin at the time.

Shaydurov indeed writes that the Russian cartridge case is based on the .338 Lapua Magnum.

Tony, I can not speak for the claim of the Russians having it copied since the involved people in Finland basically did it at the same time the Russians did.
I do not know how likely it is that Russia copied something while the Fins were still working on it.
The round in Finland started it’s life as a subcaliber load for the 102mm AMOS mortar system and only from there developed into a private venture hunting load (silenced!). Finnish officials also got to know about but for some reason did not come up with any interest it seems.

Jochem, but this is no indicator for them having taken the idea from Finland.

The rifle isnt called MKS. the MKS is a swedish machinegun/pistol that uses the magazine as “pistol grip” which it was compared to as the sniper has the same.

I’ve found the ECRA article, in issue 610 (February 2016). It reads as follows:

I was sent the following information by Vesa Toivonen, Specialist Weapon Systems Testing, Patria Land Systems Oy.

“Upon browsing the net I stumbled upon the article ”CARTRIDGES FOR SILENCED SNIPING RIFLES” written by you. The Russian 12,7x55 cartridge for “Vychlop” sniper rifle was mentioned and I thought you might find the information in the letter from the year 2002 – shown below - useful to you.”

The letter referred to explains that the 12,7x55 AMOS cartridge was developed in 2000-2001, principally by Vesa Toivonen. It was intended to be fired from a sub-calibre insert barrel round in the 120 mm twin-barrelled Advanced Mortar System, for practicing direct fire (Patria’s AMOS and NEMO turreted mortars are unusual among mortars in being able to fire at zero elevation, in direct fire).

The cartridge case was based on the .338 Lapua Magnum, shortened to 55.0 mm, and sized in a custom die made by gunsmith Jyri Jalonen; the first loading batch carried the commercial headstamp .338 LAPUA MAG , but the majority had the FDF-style (Finnish Defence Forces) LAPUA 98 stamp. The projectiles most often used were Vammas-made .510" / 850 grain solid brass bullets which closely matched the ballistics of the 120 mm mortar bomb. A very small number of bullets were made with tracers, hand-built using the sawn-off rear end of a FFV Vanäsverket´s 7,62x39 tracer bullet, which was trimmed to length/weight, glued and crimped in place – and it worked beatifully, well enough to demonstrate “proof of principle”! A batch of rounds was also loaded with Barnes .510" / 800 grain #510800A for comparison purposes.

The “gun” itself was built using a drill shell, which was equipped with a short barrel inside the tail boom (shown below). With this shell the crew would get both direct fire and dud removal training with each shot fired. The main point of the project was to provide low ammunition training costs and much smaller range safety zones in comparison to 120 mm mortar shells.

Successful ballistic testing by Patria took place in the summer of 2001, followed by a formal study carried out for the Finnish Defence Forces Materiel Command in autumn 2001, including test firings at the Niinisalo Proving Grounds. Only a small number of rounds remained after this testing.

Vesa Toivonen comments that the 12,7x55 AMOS cartridge is remarkably similar to the later Russian “invention”. The FDFMC did not adopt the 12,7x55 for training purposes. However, a Sako TRG-41 was converted (= barrel replaced with a .510” / 1-10” version and equipped with a custom-made AseUtra silencer) to 12,7x55 AMOS and featured in an article in the now-defunct gun magazine Kaliberi. Later, inspired by the article, several hunting rifles have been built in Finland for 12,7x55 AMOS using TRG or Mosin-Nagant m/91 (!) actions.

The photo on page 2 shows (from left to right): a tracer round; a tracer bullet; a solid round; a solid bullet; the case and the .338LM “mother” case.


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Okay, here’s an interesting bit from the Russian side of the 12.7mm subsonic story.

an early experimental 12.7mm subsonic load from “Vychlop” R&D program, based on 20 Ga brass case.


Here are the rounds that the Thun Arsenal reference collection. I didn’t take pictures of the headstamps with the exception of the pressure test; it’s the same D A 01 69.




P.S. thank you for informing me of this beautiful caliber. Its probably gonna take a while to get one though.

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