K31-XXI * The Ultimate Chassis

Presentation

Philosophy


Weight

The original K31 was designed as a lightweight combat rifle for mountain warfare. In a march over alpine passes, every gram of weight is a gram too much. One of the core design requirements was to keep the spirit of a lightweight mountain carbine, with zero compromise on features, ergonomics, or endurance.

We’ve done it! The chassis, fully assembled with adjustable cheek piece and shoulder pad, weights in 1300 g – less than the original wooden stock (and more than two times lighter than the nearest aluminium alloy competitor).

Respect for the legacy

The K31 is a piece of history, it deserves respect. A core design requirement was simple: no irreversible changes, no gunsmithing.

We’ve done it! No drilling, no tapping, no crippling of legend is required. At any point the rifle can return to its original wooden home, in the exact same shape as issued to the troops three generations ago.

Staying on target

Did you ever shoot a K31 long range? Did you ever wish the carbine did not jump as a mad chamois, so that you could stay on target, spot your shots, and follow-up?

Well, we’ve done it! A picture is worth 100KB of words:

The shouldering point has been raised to get it more in line with the bore axis, and minimise the muzzle jump. Before you could see where you were shooting; now you can see where you are hitting.

Modern ergonomics

Imagine an army of androids or battle clones armed with futuristic K31s. Cool, huh? Well, it does not exist. Contrary to battle androids, human shooters come in different sizes and shapes. One size does not fit all.

Now it only takes a few seconds to get your K31 just right for a featherweight sharpshooter lady or for a 2m+ 120kg+ grenadier wrestler. The adjustable cheekpad allows for a comfortable cheek wield with almost any scope mount you can find on the market, and the shoulder pad is adjustable in length (LOP from 29 to 37 cm) and in height to exactly suit each individual shooter.

Modularity

Keymod. Enough said.
Also, the pistol grip is AR15 standard – just pick any aftermarket piece you like, beavertail or not.

Scope mount and brass ejection

Director of the Federal Waffenfabrik, Colonel Brigadier Adolf Furrer, the father of the K31, has designed a truly marvellous piece of mechanical art. However, he seems to have devoted a lot of effort into making it very difficult to mount optical sights on the carbine. In the 1940s, the Waffenfabrik undertook several failed attempts to scope the K31, and gave up. The problem is that a scope installed for appropriate eye relief has to be mounted just above the ejection port. As the brass ejects almost vertically, it hits the scope mount, falls back inside the receiver, and blocks the action.

We have succeeded where the Waffenfabrik has failed. By raising the shouldering point and moving forward the natural position of the shooter’s eye, it now became possible to mount a scope (standard flattop AR15 height / 1.5″ = 38mm recommended) without hampering proper brass ejection. Those who tried would know the value.

No compromise!

In the design and manufacturing of the original K31, there were no compromise made on precision, durability and finish (as always, the Swiss make firearms way better than necessary).

The legacy lives on with the modern chassis. Aircraft-grade tempered aluminium alloy with durable hard anodising finish is calculated to withstand all rigours of field shooting; the toughness of the build is confirmed and verified with countless hours spent intensely abusing the prototypes (that was a heart-breaking sight indeed), and thousands of rounds of live fire. As the original, it just works. And looks cool.

Tech Specs


Weight: 1280 g (1325 g with a Magpul MOE pistol grip)

Material: T7075, single piece CNC machined

Coating: black anodised

Cheek pad adjustment range: 0-30 mm

Butt pad length adjustment range: 80 mm (29 to 37 cm length of pull)

Butt pad height adjustment range: ±30 mm

Pistol grip compatibility: AR15 standard, with or without beavertail

Foreend modular: 14 slot KEYMOD interface

Bagrider plane modular: 3 slot KEYMOD interface

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