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The Swiss K31...Finally.
By Joseph D'Alessandro Editor | RealGuns.Com

In the beginning...

OK, so I didn't know the Swiss produced a rifle. I know the Swiss monitor cow flatulence out of concern for methane byproduct, I know I've seen some reference to chocolate at one time or another, and Swiss watches and knives are pretty neat. Hmmm, actually, that may be the Swedes who monitor cow flatulence; I apologize for my Swiss-Swede dyslexia. I am pretty sure the K31 belongs to the Swiss and people who like guns seem to really love these rifles. I had a bunch of test equipment and three rifles laying on the bench at the range this afternoon; a K31 chambered for the 7.5x55 Swiss, a Ruger No. 1 45-70 Gov't and a BLR Browning in 243 Winchester. All morning and afternoon I had visits only from people who wanted to talk about C&R licensing or K31's.

I've been building and buying firearms for a considerable period of time, but it had been quite awhile since I spent time with unaltered military firearms, since my teens to be more precise. Several months ago I picked up a few surplus pieces for various projects, all remained intact, one was refurbished, all became good shooters and the object of a handload development effort. I got in the habit of checking the newspaper for military surplus sales, mostly those sold by a  local Big 5 that is gun friendly. The only piece I had avoided was the K31. I had somehow gotten the notion in my mind that they fired an anemic round and the straight pull action and key chain loop at the end of the bolt were quirky enough to dampen my enthusiasm for the rifle.

Eventually Big 5 ran out of Enfields, and Springfields, and Mosins, and Mausers even of Turkish descent. It was a long weekend, there was nothing on TV, so I bought one, then immediately made the mistake of trying to buy a box of ammo. I think the response was, "You're going to love this gun. I normally have ammo on hand, but for some reason I don't see any behind the counter right at this moment." Right, this or any other moment. The cartridge is the 7.5x55.6mm (GP 11) which, I learned, is Swiss for "On perpetual back order".

I set out to buy brass on the Internet and a set of dies so I would be able to handload whatever I needed.  Finding brass on backorder for several months, I instead located reasonably priced FMJ non-corrosive and reloadable cartridges and Hornady New Dimension Dies at Graf & Sons, and a copy of "For Collectors Only. Swiss Magazine Loading Rifles 1869 to 1958" from Amazon.

It takes me awhile.... bits and pieces

I like to purchase firearms, then figure out what I bought. With the rifle semi clean and laying in my lap, I began reading, identifying and pointing to it's various parts in an attempt to identify something about the gun's history. If you'll excuse a little gratuitous "blah, blah" - the K31 is not a Schmidt in the strict sense of the word, it is a redesign by a Major Furrer on the Schmidt-Rubin Model 1911, and actually quite an improvement; it is shorter. lighter and better balanced. The particular rifle I purchased weighs 9 1/2 lbs, is 43 1/2" long and has a 12 3/4" pull - chunky. Trigger pull is a clean 4.6 lbs from a trigger that is reminiscent of a screen door latch that moves in a long exaggerated  arc. The bolt cycles like a large, heavy, well oiled machine; very smooth throughout its travel and with substantial heft. According to serial number dating, this particular K 31 was manufactured in 1944; a busy year in Europe, however, apparently not too busy for Eidgenoessische, Waffenfabrik, Bern, Switzerland to produce approximately 51, 899 K 31 rifles. The K31 was produced in total between 1933 and 1958.

Nice to have a surplus rifle that isn't back bored. The K31 has a nicely recessed grown that is intended to protect the muzzle terminated surfaces of the bore. The 4 groove K31 barrel is approximately 26.450" in length, the twist rate is about 10.6". I have seen several minor variations on these dimensions, most I assume the product of various millimeter to inch conversions. The bore of the rifle I purchased is better than most of my commercial rifles, including those costing 20 times more. I understand these rifles only saw non-corrosive ammo, still, 60 years is a long time for a rifle to remain in such good condition.

The spec caliber of the K31 is 7.51mmm, which is somewhat problematic as there is no conversion relationship that will get you to the actual 306"  groove or 308" bullet the rifle utilizes. The original  chamber pressure spec for the K31 cartridge is 3200 bar or 46,000 PSI. The current CIP spec for the 7.5x55mm GP11 Swiss cartridge is 3800 bar or 55,000 PSI. Spec velocity is approximately 2600 fps with a 174 grain bullet, performance easily surpassed with safe handloads.

The front sight, pictured right, has inward curved protecting ears which is consistent with a K31, the similar but earlier Model 1911 ears are splayed outward.  Notice the stake mark that anchors the sight blade to the sight assembly, I don't think anything is going anywhere accidentally. In terms of adjustment, 1 mm of front sight horizontal adjustment shifts point of impact 12 cm at 300 meters. Front sights blades were produced in 5 different mm heights: 5.9, 6.2, 6.5, 6.8 and 7.1. The incremental change in vertical point of impact at 300 yards is 16 cm. One thing that I always find odd about military rifles is the sight adjustment as received. I worry about checking my rifle's sights when it has not been used for a while, or certainly after it had been shipped. After all, this bouncing around surely should cause sights to move. The K31 was cleaned and taken to the range with no further adjustments and shot dead on at 100 yards, windage and elevation. My Russian rifles also shot the same.

 

The absence of range markings on the rear sight base indicates it is a K31 type and consistent with the 1944 production date. The sight's range of adjustment is 100 to 1500 meters, indexed in 50 meter increments. Unlike the rear sights on my Turkish Mauser, the pieces don't rattle around, they lock up well and are solid in use.

Other identifying items like finger groove offset, trigger guard and butt plate size, shape and placement all track to a K 31. I removed the butt plate looking for the owner identification information that is sometimes found, however, all I found was a date stamp for the stock, October 1948, which suggests the gun was refurbished or fitted with a replacement stock. The stock is not walnut, it is birch, which would be consistent with the "X" and "1948" stamps. I'm not worried about the lack of stock originality. I'm not sure when the change to this particular gun was made; could have been at Century Arms, could have been in 1948, but it still looks OK and better than a replacement of modern manufacture. A quick check of a replacement walnut utility grade stock found a $159 price tag for stock and handguard, with a lot of fitting work required. With that additional information I, of course, grew to appreciate the near authentic looks of the stock that came with the $89 rifle even more.

There are a few unique external aspects of the  K31, in addition to the straight pull operation. 1) Bolt release, 2) Cam follower handle, not bolt handle, 3) cocking ring, 4) stripper clip, or charger,  cut out in receiver.

The bolt is removed by pulling it rearward, then depressing the bolt release latch. The cam follower does not serve the same purpose as the bolt handle on a classic  turn bolt rifle and is therefore not called a bolt handle. A bolt handle is affixed to a bolt body and rotated the body to lock and release locking lugs. In this straight pull scheme, the cam follower rotates the bolt's locking sleeve and lugs, camming them into position. The cocking ring, when the rifle is cocked, can be rotated clockwise to obstruct forward travel of the cocking piece sear and lock the bolt in the closed position; the safety.

As the straight pull operation is the central theme of this firearm, I thought I would take a few moments to provide a little more detail and see if I can't confuse everyone. The cam follower provides a couple of functions. The cam follower pin (2) travels in the bolt locking sleeve's helical groove. Pushing the follower forward carries the bolt assembly forward in the action while rotating the locking sleeve and locking lugs (4) clockwise into the receiver's locking lug slots, Pulling aft on the cam follower reverses the direction of the locking sleeve, pulls the lugs out of the locking lug slots and releases the bolt. The cutout at the end of the follower (3) prevents the bolt from being removed from the rifle until the spring loaded bolt release latch is depressed and clears the cutout.

The operation isn't actually that weird, although it takes a little adjustment to overcome turn bolt operation tendencies. If you've shot a Browning lever gun you will find a similar rotating bolt sleeve and locking lugs that translate the fore and aft motion of the operating lever to the rotating motion of the bolt's locking lugs. The assembly cocks on opening.

The K31 was one of several military rifles produced with a straight pull action. Other notables are the preceding generations of Schmidt-Rubin rifles, Canadian Ross, Winchester Lee  and Steyr Mannlicher M95. It is hard to say what exactly the straight pull has to offer. Speed of follow up shots is the first suggestion typically put forth, followed by smoothness of operation. The first draw back referenced is that the straight pull does not have the mechanical advantage of a turn bolt action, the second is that the straight pull is based on a more complicated mechanical assembly.

Personally, my sentiments are: the action is very smooth, I can't feel a practical speed advantage, I can't see where the assembly is much more complex than a turn bolt gun with its own complex innards. In the court of public opinion the Swiss rifle is the only straight pull that endured for so long as a military weapon, the others fell by the wayside as the weapon of choice for armies that actually saw combat, the Swiss version never did. People with their lives on the line, on critical missions, tend to shed the fluff and go with the essentials. So what's the point? I think anyone looking for blinding speed or bench rest accuracy as a result of straight pull design may be disappointed in the K31. Anyone interested in well made Swiss machinery, better than average accuracy and something unique in operations will find themselves pleased with the K31.

Most K31s of this vintage have hellacious scratches that run from the butt plate upward about 4" and mine is no exception. There really is no mystery, the marks are the results of soldiers drilling with hob nailed boots. I have seen illustrations of the drill, and the boots and the results. What does this mean? Only that most of these great looking rifles are diminished in appearance by abusive handling. I may try to sand some of them out, but probably not. There isn't sufficient material above the sides of the butt plate for refinishing and the cost of a replacement stock is prohibitive, or at least not practical. The balance of the wood, and certainly the metal parts are in excellent shape with barely signs of wear.

 

The K31 holds 6 rounds in its detachable, the mag is easy to insert and remove. The bolt will not close on an empty mag unless the shooter depresses the mag follower while pushing in on the bolt...which may result in the Swiss version of the M1 Thumb.

Check out the trigger. That has got to be the longest trigger I've ever seen. For me, pull isn't so great, but I may just need to practice more with the rifle. It is smooth, but it feel springy and too lightly sear loaded.

The trigger guard is Swiss practical, or stamped steel cheap, depending on your perspective.

Range Time

Due to equipment problems beyond my control, and an errant software setting, I was able to spend more time than intended with the K31. Shooting it was an interesting experience. The first shot missed the target. What I thought was a nick in the rear sight was actually the notch for aiming, and that slightly left listing post up front was, in fact the sight blade. One I had that sorted out, even with less than stellar eyesight I was able to shoot inch to inch and one half 3 shot groups at 50 yards. For my open sight skills and off the shelf cheap ammo and an unfamiliar rifle, that's pretty good. In fact, I was impressed.

There was very little recoil. The short pull and full length stock with handguard gave the gun a slight nose heavy feel; steadying more than uncomfortable in balance. The action was slick in use and fed and extracted without a hitch. The only thing I noticed is that the bolt needs to be opened firmly or there is the chance of an empty flipping over in the action and not ejecting. That only happened once when I was trying to cycle more easily to avoid chasing empties around behind the firing line.

The Prv Partizan ammo appeared to be very good quality Serbian production. These cartridges have boxer primers, they are non-corrosive and, at $14/box, not all that expensive to shoot. This particular load is 174 grains FMJ BT with a MV of about 2600 fps. Sounds familiar? They are also producing a soft point load, however, it is relatively new and I found none in stock. Hornady and Graf&Sons is loading a soft point also, for about $5 per box more. My primary purpose for getting ammo was to eventually get empty brass.

Of the non-U.S. military surplus rifles I've been able to shoot over some period of time, this one ranks second to the Model 38 Mosin Nagant in entertainment value, although the K31 has an edge in accuracy, but not a huge edge. I'm looking forward to handloading some ammo and seeing what I can wring out in ballistic performance and consistency. I'm thinking 165 grains at 2900 fps without exceeding pressure specs. We'll see.

There are scope mounts for the K31; a right side clamp on from St. Marie Graphics, a left side drill and tap from the same, and one of the mounts that hangs on the rear metallic sight mount. None of these looked very appealing or in anyway similar to the scoped version of the K31 and none are in the cards for this particular gun. I think the metallic sights are fine for any use the gun might see, including eastern U.S. hunting although I wouldn't relish the thought of dragging this one around in the woods.

Conclusions

The K31 is a very nice military surplus piece and an excellent bargain. The specimens I've seen are in much better shape that other popular models sold through discount C&R dealers or retailers, particularly bore condition and metal finish. Stocks are a bit ratty, but functionally fine if they are not cracked. Because of their accuracy and solid feel K31s are enjoyable to shoot and the 7.5 Swiss is a pretty potent cartridge. The down sides are weight, inability to easily and properly mount a scope and lack of sporter potential for those who might be so inclined. It is a strong action, but I would not want to crank this one up; two locking lugs and a straight pull action. The gun actually has not much of a history. It saw no combat, so it's value was not proven under survival circumstances. Basically, it was the weapon of choice of an army that never went to war. I think some folks have unjustifiably elevated this relic to almost mystical levels with unfounded stories of Swiss precision and unrealistic tales of accuracy. It is a $89 rifle, if it didn't have a lot of compromises and limitations in use it would be a $500 milsurp rifle. Still, in the land of affordable imported relics, I would rank it the best of the readily available military rifles out there.

More K31 info on Real Guns:

7.5x55 Swiss Handloads
7.5x55mm Swiss Handload Data

 

 

 
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