K31 Dies for 7.5x55 Swiss

Who reloads for their K31 and what dies do you use?

I have read about the (alleged?) difference between K31 and other 7.5x55 Swiss chambers and that particular dies are best if one wants to minimize working the brass. The problem I found is the Hornady K31-specific die set (their number 546361) is not in production and they say they don't know what they'll make more of them and the Redding is pretty expensive.

My question is: is there another alternative to those 2 for K31-specific dies?

I'm not desperate - I have enough GP11 for this shooting season and well beyond - but I want to get ready to reload.

Any decent 7.5x55 sizing die will work just fine for the K31. The idea that only the Hornady or Redding die is correct for the K31 chamber has been way overdone at some sites. In practice, the most often cited benefit of the wide-shouldered "K31" die is very slight - for the simple reason that it works the neck no more or less than a 1911-style die and it's the neck that fails first from work-hardening, not the shoulder. Proper annealing takes care of both neck and shoulder - and has to be done for the neck anyway, long before the shoulder actually needs it.

Those who argue that the "K31" die necessarily gives greater accuracy fail to recognize that a carefully FL-sized cartridge is centered by the cone of the case shoulder mating with the cone of the chamber shoulder. This occurs whether the major shoulder diameter is .455" from a 1911-type die or .472" from a "K31" die.

A few handloaders claim that the "K31" die, by doing less work, requires less force on the press handle. That's undoubtedly true - but if you use the right lube, sizing a K31-fired case in a 1911 die isn't difficult anyway. Of course some handloaders are addicted to pretty ineffective case lubes and aren't eager to change to one that works better and costs less (e.g. castor oil).

The only practical difference is that cases fired in a K31 normally elongate more during FL sizing in a 1911-type die than in the "K31" die. Brass displaced when shoulder diameter is reduced goes in the only direction open to it during sizing - forward. Consequently, less frequent trimming is required with the die that reduces the shoulder less. Many careful handloaders trim often simply for greater uniformity. Those who find trimming especially onerous are probably better off with the larger "K31" sizer.

Thanks for the details, parashooter. I'll keep thinking about this.

I wound up buying a Redding set and have run a small batch of GP11 brass through the sizing die. Will make some test rounds to validate that I can do all the steps and set a Berdan primer to the right depth and make something that goes bang safely. I don't have any Berger VLD bullets so I'll try either some 168gr or 175gr Nosler CC's that I have. Another challenge will be to find the right bullet seating depth since the ogive is not the same as the VLD.

Just be aware that the K-31 (and the ZfK-55) have SHORT throats that are meant to accommodate the GP-11 bullet with its SECANT ogive.

Any suitably-weighted bullet with a TANGENT ogive, like the Sierra Match-King series, will probably give you problems with seating / overall length measurements. A K-31-owning friend found this out the hard way after he loaded up a batch of ammo with 168gn Sierra MatchKings and the found they would not chamber. They fed fine through K-11s, both his and mine.

The earlier G / K-11 series have a LONG throat because, when they were introduced, there was still a vast amount of the earlier "torpedo"-bulleted ammo in the system.

Lee Enfield owners will also be aware that this happened with their favourite rifles. The long throat needed for the round-nosed Mk6 bullet was carried over in the SMLE series until final production. No4s seem to have a throat more appropriate for the profile of the MK7 bullet.

The US "Springfield" went through the same transition: the first '03 was chambered for the same long, heavy round-nosed bullet style that everybody else was using.

Then those craft German chaps turned the ballistic world on its ear and introduced "spitzer" bullets driven at considerably higher velocities. Thus, everyone who wanted to stay in the game had to turn around and re-engineer their rifles and machine-guns (sights, feed systems for starters), and re-think their range tables.

Hence "'03-A3" Springfields.

Oh, and regarding dies, I use the Lee version for my K-11 reloads.

Well-made gear; no problems here.

I doubt there is any significant difference in CHAMBER dimensions between the K-11 and the K-31. Throats; yes; chambers; no.

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Originally Posted by Bruce_in_Oz

. . . I doubt there is any significant difference in CHAMBER dimensions between the K-11 and the K-31. Throats; yes; chambers; no.

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There is a significant difference in taper and consequent diameter at the body/shoulder junction -

https://www.milsurps.com/images/impo.../25jfpsz-1.jpg

FWIW, the GP11 bullet features a tangent ogive, not secant. It's a long-radius ogive that begins pretty far back, but it's a tangent.

https://www.milsurps.com/images/impo.../2ztilbt-1.jpg

https://www.milsurps.com/images/impo...5/1hf41u-1.jpg

Well, there ya go!

Except....

By that diagram, there is NO parallel bearing surface anywhere on that bullet; there is a slight taper starting at the forward end of the boat-tail. This then changes to the 70mm ogive radius..

So, the GP-11 bullet is not your "basic" bullet by a long shot. I don't have a CAD package on this computer yet, so, is anyone out there capable of whizzing up a quick (but accurate) profile from the sketch provided in order to ascertain exactly where that 70mm ogive radius runs?

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Originally Posted by Bruce_in_Oz

. . . there is a slight taper starting at the forward end of the boat-tail. This then changes to the 70mm ogive radius.

. . . is anyone out there capable of whizzing up a quick (but accurate) profile from the sketch provided in order to ascertain exactly where that 70mm ogive radius runs?

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That "sketch" is a vintage Swiss mechanical drawing that accurately describes what we find when measuring GP11 bullets - "a slight taper starting at the forward end of the boat-tail" that "changes to the 70mm ogive radius" after some 6.2mm of a conical section 7.82mm diameter at its base and 7.70mm at the tangent ogive junction. While the design may be too unusual for some tastes, the Swiss seem to have been pleased enough to keep it in service for over 80 years - essentially unchanged except for playing around with cannelures.

Attachment 62483
GP11 bullet variations from 1911 to 1978

GP-11: Worked for them since 1911; last heard of still feeding the "Rolex-grade" MG-51 GPMG as well as a slowly diminishing fleet of "Reserve" K-31s, ZfK-55s, StG-57s etc.

These bullets should work quite well in a .30-06.

I would definitely not be complaining were the elves to leave a pallet of those "oddly-constructed" GP-11 bullets under my Christmas Tree.

The good wife may inquire about where her .224" 69gn SMKs were, however.

The dies that load 1911 etc. work fine for a K31 but not the converse. The ones I have are LEE both Full length and Collet neck sizing. I have found that you can not size a K31 fired case too much. Too little and you work the rifle too hard, slamming the bolt home. What is the better deal, K31 operating rod or a few brass cases? The K31 specific dies are fine, but as Parashooter said, it is a solution looking for a problem. If you buy a 1911 or 96/11 rifle, you will need the earlier type of die.

Dave

This would indicate one or more things:

1. The Swiss undertook a MASSIVE workshop programme to update the hundreds of thousands of G and K-11s in service to accommodate "later" ammo of the same designation for the K-31.

2. CIP have stuffed up.

3. Lee have stuffed up and not done their homework.

4. GP-11 cases are made to be a bit of a "racing fit" in the older chambers and 'perfect" for the K-31.

5. Something else is afoot.

Anyone have the data for the chambers in the StG-57 and Mg-51? Yes, I know they are kinky, fluted jobs (16 flutes as I recall, as opposed to twelve in a H&K), but The Swiss fielded EVERYTHING from the 96/11 to the Stg57 simultaneously for well over two decades. Even the advent of their 5.56 beasties has not yet seen the total demise / selling off of the older 7.5 rifles. The MG-51 is still around, also to be found in 7.62 NATO.

Bruce,

1) My research is that the shoulder area of the K31 is wider than the earlier rifles. Why this was done I do not have the data. Maybe they analyzed the WW1 data and thought that trench mud might muck up the precise tolerances and made the chambers "sloppy" to accommodate dirt etc when designing the K31? Given that the ammunition was already in use for 20 years, and there were plenty of older and even war use only really old rifles that would chamber the existing ammunition, a new size was not instituted to match the K31. Somewhat like firing a 38 special in a 357 magnum, works just fine, although more like a 38 Super in a 38 Colt ACP pressure wise for the really early rifles.

2) CIP not likely to mess up, one GP-11 and that's it (excluding blanks, grenade rounds etc.).

3) Lee F/L dies load ammo that matches (as close as possible) the original size of the GP-11 (not sure if the - is needed?). This means that my reloads would work in G96/11, K11, 1911 rifle, K31 and during their Swiss reserve use in a war emergency the earlier rifles that used GP90, GP 90/03 and GP 90/23 (not today in these rifles unless hand loaded to the proper specs).

4) GP-11 fits all chambers. Reloads using a K31 specific die probably will not chamber in the earlier rifles.

5) Nothing I know is afoot except that "working the brass" is an internet, bar stool, or "I know more than you" recitation that has little basis in fact. Does brass work harden? You bet. Is it a problem in a K31? Not in my limited experience. My full length sized nny (Prvi) brass having eight reloads using the LEE F/L dies and no neck or shoulder cracking and one anneal after five cycles. I can tell you that neck sizing K31 fired brass at full power will not work like it would in a Springfield 30-06, SMLE 303 British or Kar98k Mauser. One loading maybe and then it is a hard slam to get the bolt to close properly. Not what I really want to do, tough on me and the rifle.

I can not comment on later Swiss 7.5x55 chambered weapons. Probably like the K31, shoot the ammo and throw the brass away. I don't know if modern military units would reload fired brass, probably not.

Dave

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Originally Posted by Wineman

I don't know if modern military units would reload fired brass, probably not.

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I vaguely recall that the Swedes had a programme of reloading their 6.5 x 55 brass as "practice ammo" and with "gallery loads" at one stage. Don't have a clue about anybody else.

My Privi 7.5 Swiss brass has been around the block quite a few times as well. I ran one small batch through my K-11 and then the Lee FLS dies 8 times before I spotted the first tiny neck crack. It has proven to be quality merchandise. I also torture it that extra bit by using the Lee "Factory Crimp" die for positive retention.

Basic drill now; ALWAYS inspect the cases before reloading, usually anneal after 6 firings.

Bruce,

Ed Harris said that his research showed that USA National guard units did reload short range practice and "guard" ammo. In the 1930's when the M1 ammo (173 grain boat tail modeled after the Swiss BT) came into use it began to overshoot the ends of the NG ranges. Well that was what it was supposed to do, shoot accurately for a much longer range than the M1906 150 grain ammo. The answer was apparently the M2 Ball 150's. The AP 168's were probably the best of the lot: heavy enough to shoot far, but not quite as far as the M1.

Dave

I use the LEE dies for the K11, 1911, and 96/11

My reloads using the Hornady K-31 specific sizer will NOT chamber in anything but the K31. They get stuck pretty bad. Found this out the hard way at the range. (This was an accident, I hadn't properly labeled the loads as having been loaded with the Hornady die set)

The Hornady sizer works the brass less, so I do use it for all my K31 loads. I figure the brass will last a little longer if it isn't worked as much. If I am wrong, no harm done. It doesn't cost me anything, and it takes less force to size the brass. Less work done on my part :)

If I take a case that was fired in the K31 and size it with the LEE die, MAN, I can really tell that it works it a lot more.

Maybe the Swiss decided that NOBODY picks up their brass on the two-way rifle range and decided to opt for guaranteed "reliability" over the wishes of hard-core reloaders and technical "purists".

I seem to recall that there was a certain amount of fooling around with .303 chambers during the First Great Unpleasantness as well.

Oddly enough, they had to deal with TWO types of ammo (Mk6 and Mk7) in the rifles, on top of appalling environmental conditions. See also the Ross Rifle saga.

CH4D makes dies specifically for the K-31. They are listed as 7.5 X 55 Swiss K-31. The dies for 1911's rifles and K-11 carbine's are listed as 7.5 X 55 Swiss. Great company, been around a long time.
If you have any questions, E-mail or phone Dave Davison , the owner, and he can answer any question about reloading dies. Super nice people and a pleasure doing business with them. I own a lot of CH dies and they are my preferred. Call them before you order and they can advise you which ones are proper. Buying the wrong anything is a bummer.
If you want a perfect fit to your rifle , just send 3 or 4 cases fired from your rifle and Dave will make the die to match the tolerances of your rifles chamber and you can then reload perfect ammunition without overworking the brass.
Gary

Having tried both the RCBS and Lee dies, they don't work in a K31.

RCBS techs confirmed their dies are cut for the 1889 spec and the Lee dies will not accept a brand case, not to mention one fired in my mint K31.

The Lee collet die (neck sizing) works fine with my K 31

I note that Hornady makes at least three different spec dies for sale on Amazon.

Lee and RCBS dies work great in my K31's. Maybe you need better lube (castor oil), or to do a bit of polishing on the sizer interior. New dies these days are often a bit rough.

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. . . and the Lee dies will not accept a brand case . . .

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Please explain what you mean by "a brand case". Makes no sense as written.

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Originally Posted by Parashooter

Please explain what you mean by "a brand case". Makes no sense as written.

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Perhaps he means "brand new case" it's all I can think of in the context.

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Originally Posted by Bruce_in_Oz

Any suitably-weighted bullet with a TANGENT ogive, like the Sierra Match-King series, will probably give you problems with seating / overall length measurements. ...they would not chamber. They fed fine through K-11s, both his and mine.

The earlier G / K-11 series have a LONG throat because, when they were introduced, there was still a vast amount of the earlier "torpedo"-bulleted ammo in the system.

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I understand (I think!) that Sierra MKs are less than ideal (don't work?) for reloading GP-11 for the K31, but are OK reloading GP-11 for the 1911, right?

If that is correct, what are some appropriate secant-ogive projectiles to use in reloading GP-11 for the K31?

Hornady produce several Secant ogive bullets in .308" size.

Anything from 150 to 175gn be it FMJ, HP or SP should work.

Here in Oz, a local bullet maker, BJD, does a very nice 155gn HP with a scant ogive that is primarily used by "full-bore" (.308 / 7.62 NATO) target shooters, who often work out to 900 yds. They work OK in the K-31. (As well as my trusty old K-11)

These bullets, called the HBC (high ballistic coefficient) have been sent to the US and Canada in SMALL batches; ask around and check the inter-tubes.

Those HBC, secant ogive bullets, here

The SMK's are fine for a K31, they must be seated deeper than a VLD bullet but they work just fine. I had a pile pulled from M118LR ammo and I knocked over 10 rams at 550 yards, 10 pigs at 330 yards eight chickens (really you missed two up close @3%*) at 220 yards and was working on the Turkeys at 400 yards when the thunder storm ended my best day at the silhouette range. K31's seem to cause issues. Think of them as a pump rifle (tight chamber, no camming action, OAL important) and you cant go wrong. Always full length size, seat appropriately, and quit worrying about overworking the brass with regular 7.5x55 Swiss dies and they are lots of fun. If you have K31 dies even better, but you need other dies for your K11, 96/11 and G11's. They have great bores, exquisite craftsmanship, and a panache that few other military rifles have. If you have a stash of GP-11 cool, if not Prvi has brass, there are zillions of 30 caliber bullets, and any powder that gets you a safe 2,500 fps with 45 grains and a 175 grain bullet is a go to. Shooting cast bullets successfully really requires a Jedi mind trick. No throat and little tolerance for neck sized cases makes for a tricky situation. Enjoy.

Dave

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Then those craft German chaps turned the ballistic world on its ear and introduced "spitzer" bullets driven at considerably higher velocities. Thus, everyone who wanted to stay in the game had to turn around and re-engineer their rifles and machine-guns (sights, feed systems for starters), and re-think their range tables.

Hence "'03-A3" Springfields.

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Bruce: I know this is older thread but I feel the need to correct things.

I believe you are mixing up Pre WWI and WWII rifles and the cartridge history.

The original cartridge for the 1903 was the 30-03. That was the 220 gr.

The 1903-A3 is a WWII Remington (mostly) modified 1903 for faster production as well as rear peep sight ala the M1.

It was actually the French who0 started the move to sharp bullets, the Germans took that and went further.

The US then followed, modified the 30-03 Cartridge slightly and turned it into the 30-06 (date of mod)

To the best of my knowledge, they made no changes to the chamber as far as accommodation the rounds. The 06 case was shorter, which allowed them to cut a thread off existent barrels (a fair number) and change them to 06.

---------- Post added at 10:43 AM ---------- Previous post was at 10:34 AM ----------

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I can not comment on later Swiss 7.5x55 chambered weapons. Probably like the K31, shoot the ammo and throw the brass away. I don't know if modern military units would reload fired brass, probably not.

Dave

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GP11 is Berdon primed and not intended to be reloaded, it can be with various tools or converted to Boxer (I believe) so re-use was never an issue. With PPU available there really is no point other than sad to see the GP11 cases go to waste but the work to convert and the primers in my opinion make that a total waster of time (some do it, vastly more time than I have)

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Originally Posted by RC20

GP11 is Berdon primed and not intended to be reloaded, it can be with various tools or converted to Boxer (I believe) so re-use was never an issue. With PPU available there really is no point other than sad to see the GP11 cases go to waste but the work to convert and the primers in my opinion make that a total waster of time (some do it, vastly more time than I have)

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The only 'time' investment is the initial setting up of the RCBS decapper, finding the best depth and angle for the pin. Once that is tweaked, just pop away.
:thup:
Using the RCBS Berdan decapper while sitting comfortably in my easy chair and watching TV, I can conveniently and fairly quickly decap GP-11 brass at at least the same or even faster pace than Boxer-primed (which of course requires using the decapping press at my reloading bench). Not having to use a press with the Berdan means I can do it anywhere.
I use my Lee Auto-Prime for either Tula KV-7.62N or PMC LARGE RIFLE BERDAN primers. Both work just fine. I will continue reloading the GP-11 until I run out of primers (8,000 on hand, but I also use them for some very nice FN 7mm Mauser brass), and then start using my untapped inventory of RUAG GP-11 crates, and just say good-bye to that brass after shooting.
I suppose eventually turning to PPU cases, which I know from my other calibers is really good brass, too.