Swiss K31 Straight-Pull 7.5x55 Rifle History

One of the all-time great straight-pull rifles is the Swiss K31 in 7.5x55. The K31 was beautifully finished inside and out and is usually found in very nice condition with excellent barrels still full of life. Citizen-soldiers issued the K31 cared for them very well, and they are rarely found out of order or heavily worn.

Normally, here I would regale you with thrilling accounts of actions involving these rifles. Except there aren’t any. Switzerland has maintained peace with its neighbors for centuries, and there are few tales associated with the small arms beyond thoughtful design.

Yet the threats were real, and the K31 was kept at the ready all during World War II, when Switzerland was surrounded by German-occupied Europe and Fascist Italy. While the Allies were hot on the Axis heels, the Swiss must have felt like a big, fat steak in front of a hungry wolf, but they did have a citizenry ready to muster armed with one of the best battle rifles of the era.

The K31 is as fast or faster to fire than the Lee Enfield, lacking only a commensurate payload. While other straight pulls have conventional bolt knobs, the Swiss early on thought more uniquely. Straight-pull mechanisms usually require more effort than turn-bolt designs, and the Swiss bolt has a comfortable aluminum “T” handle to pull.

The position of the giant ring at the back shows at a glance to shooter or observer whether the rifle is cocked, uncocked or on Safe. The pull weight to open the bolt after firing is 23 pounds, measured with an RCBS machine gun trigger pull gauge. The bolt is numbered to the gun.

This giant ring is large enough for gloved hands, but one flaw is that engaging and disengaging the safety is awkward for right-handers. The ring, which requires 16 pounds of effort to draw, is pulled and turned 45 degrees to the right to apply, and you have to reach over it to manipulate it. From a rest, it is easily manipulated left-handed.

When the rifle is on Safe, the trigger is disconnected and the bolt locked closed. In the event of a misfire, a yank on the ring cocks the rifle for a second try. The two-stage trigger has a lot of light take-up before breaking crisply at five pounds. The trigger assembly is one of the most complex ever put into a military rifle, and the let-off is exquisite.

The rifle is heavy at nine pounds, 15 ounces unloaded, yet it handles well and the balance is right between the hands. At 43.5 inches long, it is a handy carbine length, but it is a wide rifle measuring a good two inches across the widest part. A quick taper and thoughtful finger grooves placed right at the balance point ease one-hand carry in addition to aiming, but it still feels bulky. As befits a rifle designed for cold weather use, the length of pull is a short 12.5 inches.

The 255/8–inch four-groove barrel has a 1:10.63 twist, open sights with a U-notch rear adjustable for elevation only and graduated from 100 to 1,500 meters with an adjustment wheel under the leaf to fine-tune the zero. The post front sight is uniquely adjustable for windage by drifting the sight forward or backward in an angled dovetail.

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On a good day, I can hold about 2.5 m.o.a. at 100 yards with surplus GP 11 ball ammunition. These rifles will often shoot much better with the addition of aperture sights.

The follower of the six-shot magazine holds the bolt open after the last shot, and it’s recharged from the top singly or by a strange-looking, fragile six-shot charger made of tin and papier-mâché. Very complex for a single-use item, these chargers were never used in anger, and they’re often found in nice condition—with new ones made of plastic available from Numrich or Northridge International.

The easily detachable magazine is held in place on the right side by a spring latch to a trigger guard, and the bottom metal is stamped from heavy-gauge sheet metal. Although the magazine extends about an inch below the rifle, it is nicely contoured with rounded edges and not prone to snagging or causing discomfort. The rifle came with one magazine numbered to the gun.

The locking lugs are on an external sleeve with an angled slot machined into it, and the bolt head with extractor rides in this sleeve but has a straight slot. The bolt handle has a long bar with a tab that runs in both slots, and it attaches to the cocking ring/striker assembly at the back.

As the bolt handle is drawn back, it withdraws the firing pin/striker assembly as the tab rotates the bolt sleeve to unlock the lugs but maintains the interior bolt level for extraction/ejection. The receiver-mounted ejector rises into matching slots at six o’clock in the bolt sleeve and bolt at the end of the pair’s travel to eject the cartridge. Pushing the bolt handle forward hands off the striker to the sear, strips off a fresh cartridge and cams the locking lugs.

In the Fire position, the bolt can be opened and closed at will. This external bar with the bolt handle at its rear rides in a slot machined into the receiver and is fully protected when the bolt is closed. The bolt can be field-stripped without tools.

Stocks were made from walnut early on, but by far the majority are stocked in a light-colored beech. The wood was given a simple oil finish. The steel buttplate is left in the white and held by two screws.

There’s plenty of unique kit for the collector. A quiet, one-hand adjustable leather sling used an aluminum button to adjust lengths for the varied layers of summer or winter clothing. The Model 1918 bayonet is reasonably priced, as nicely made as the rifle, and features an 117/8-inch double-edged blade in a steel scabbard.

A six-pouch bandolier holding 12 clips was issued to bicycle troops. Sadly, my bandolier had been in storage a long time, and the leather dried out. Thankfully, it had no cracks, and patient application of leather conditioner brought it back to suppleness.

Not so practical in use, the bandolier goes over the shoulder, and a loop holds it to the waist belt so six clips are in the three front pouches, but you can’t reach the other six in a hurry. Aluminum buttons hold the pouch flaps closed.

Cleaning kits in cloth pouches come with a nifty mirror bore reflector, a pull through, a scouring stick for a rusty chamber and a grease can. Muzzle protectors are another easy find.

The 7.5x55 cartridge is in the .308 class, and the load for the K31 was the GP 11, named for Gewehrpatrone 11 after its finalized design in 1911. The Berdan-primed cartridge features a still-modern 174-grain spitzer boattail at about 2,650 fps. Ammunition came in 60-round battle packs with six 10-round boxes, and the clips hold six rounds.

Prvi Partisan and Norma offer new Boxer-primed ammunition, and the K31 is easy to reload. With the fast twist barrel, a wide variety of standard 0.308-inch bullets may be used. All the major companies offer reloading dies and data.

More than 580,000 K31 rifles were made between 1933 and 1958, and many stayed in reserve store until the 1990s. Another fun, unique element found with some rifles is a piece of paper under the buttplate with the name and address of the last citizen/soldier issued the rifle.

Because the papers are not attached to the rifle, some dealers have pulled out the papers and put them under the buttplates of higher-condition rifles to increase their value, but sometimes the rifle’s serial number was recorded on the tag, as it is on my sample. 

Few of their rifles have been sporterized because they’re so heavy. Some have had diopter-style sights added for target shooting, but the majority have been left in their original military guise. Prices are relatively low for the build quality, and most have the majority of their original finish—making the K31 an excellent and very beautiful entry level collector/shooter.