Swiss K31: Check new brass length after its first firing & resizing

[Linstrum]

My latest rifle is a Swiss K31 and I have only run 20 rounds through it so far. I usually reload brass in 20-round lots, so when I fired the 20th round it was time to reload for my K31. I had originally started out with new brass and I checked it for length before loading the first cartridge, and they were all right around 2.185" where they were supposed to be. I have not had any of my brass "grow" much during its life, on the average I probably trim the brass after maybe the fourth or fifth reloading and every three of four reloadings after that until I get an incipient head separation and have to relegate those cartridges for making kids' pocket whistles and powder dippers. This lulled me into getting slack in checking my used brass length and I had a pretty rude awakening when I tried to chamber one of the twenty cartridges I had just finished reloading. They were all once-fired cartridges that I had run through my 7.5x55 Swiss sizing die and then reloaded without first checking case length. Why? Because in the forty-something years of reloading I have never had to trim after the first firing! I guess I beat the odds on that one by a long shot, for sure. If I owned a British .303 that might have been a different story, but I don't have a .303. At first I thought that I didn't have the bullet inserted deeply enough in the neck since the Swiss K31 rifles do not have any free bore and projectile ogive interference is a problem with the K31 rifle. That is what I thought my problem was when I couldn't get the bolt to close, but my "little red warning light" in the back of my mind started to flash brightly since most bolts have enough camming action to shove the projectile further into the neck or into the rifling, or both. I knew beforehand that brute force is NEVER the answer and I was prepared to have the bullet get stuck in the bore, but that didn't happen. On a hunch I got out my dial calipers and checked the case length and found that it had grown by a whopping 0.025". I checked them all and every one of them was now at 2.210". Man! Not taking a minute to check case length after re-sizing just cost me about two hours work in having to pull down 20 cartridges in order to trim the brass. Why so long since pulling bullets is not a big deal? The insides of my brass are sticky from case lube inside the necks and the little bit of powder stuck inside the case will force me to disassemble, trim, and then reassemble the cartridge with the same charge of powder that came out of it, otherwise I won't know how much powder is inside each cartridge and I might have a dangerous overload in one of them, so I will have to do each one individually instead of in a much faster assembly line fashion.

The morals of the story are: 1 - If you have a Swiss K31 check your brass after the first resizing like you would for a British Lee Enfield. 2 - Just because you haven't had something happen in forty-something years doesn't mean it won't happen eventually!


rl705

[Calamity Jake]

"On a hunch I got out my dial calipers and checked the case length and found that it had grown by a whopping 0.025"

If the cases had grown that much at firing then you would see signs of comming head seperation.
I think the growth came from pulling the case back over the expander ball after sizing
or your dies are not designed for the K31 chamber as Redding is the only company that makes
a true K31 sizer the others are for the K11.
Also if the expander ball is pulling the neck forward then it is also changing the shoulder angle. If your size die is correct then make sure it pushes the shoulder back a small amount.
Your 40+ years of reloading has my 30+ beat but that doesn't stop some thing from slipping
up on us.

My 2 K31's require me to full length size cases to insure good function.

[beemer]

Check the dia. of the case at the shoulder of an unfired case and one fired in your rifle. The difference of an unfired GP11 and a case fired in my rifle is close to 20 thousands of an inch. You didn't mention the brand of dies but it can make a difference. When the case is fired the brass stretches out to fit the large shoulder, when sized back to fit a 1911 the brass has to go somewhere and it flows forward. All cases grow some but heavy sizing amplifies the problem.

I have a set of dies designed for the 1911 and a set Redding dies. The Redding dies work the brass, especially the body of the case very little. There has been a lot of discussion about the dies but I found what works for me.

I hope you enjoy your new rifle, they are a little different but that's what make them fun.

Dave

[mike in co]

i'll second that...WHAT BRAND OF DIES ???

[462]

I use Lee's collet neck sizer die and have never had a case grow. I have two k-31's and keep the brass segregated.

[Bob S]

After reading this post, I checked 20 cases before loading/firing and after firing and FL resizing in ancient CH dies, the cases grew an average of 0.002". Cases were reformed 284's and this lot of cases had been reloaded 5 times prior to this.

Resp'y,
Bob S.

[3006guns]

I had a similar occurance with my K31.......on the first loading! The brass was from Grafs and I gleefully assembled a number of rounds, only to find the bolt wouldn't go fully into battery. New cases are supposed to be already sized.....right? Well, they WERE right. It was the infamous "non throat" of the Swiss rifle, which I was unaware of at that time. I seated the j-words just a touch deeper and no more problems.

Point is, from now on I will never assume (there's that word again) anything and full length resize and check for functioning before proceeding to load powder, primer and projectile.

Like the poster.....40 years in this hobby and you still don't "know it all"!

[mike in co]

inquiring minds want to know....who's dies ????


i'm betting not redding........


mike in co

[Linstrum]

Hi, guys, thanks for the input, it is always appreciated!

Ricochet and I have been comparing notes about Swiss rifles, and what he related to me is pretty much what was said here. The 1931 chamber is a bit different from the chamber used in the 1911, and the K31 chamber was larger but held to tighter manufacturing tolerances.

As soon as I had trouble I made darn sure that the die set I was using was for the 7.5x55 Swiss cartridge since it took way more force to run the cartridge in than what I'm used to, and I had to resort to using good old sticky, gooey lanolin as the case lube. No, the 7.5x55 Swiss dies are not Redding. I got the Lee 7.5x55 Swiss dies off the shelf the day I picked up my K31. This is the first time I used the sizing die in the set since the sizing die was not required for loading the first batch of ammo using new Prvi brass like Ricochet has been using for his K31. That I had trouble with the dies sizing far more than was necessary came as a nasty surprise since I normally get way, way more than two reloads per cartridge case using Lee dies in my other milsurps. From my past experience, I had no second thoughts about using Lee dies for the Swiss K31 since up until now they haven't worked the brass to death in any of my other rifles. I realize that cartridge life is not a simple thing based solely on the reloading dies used, it is from a combination of several factors not all completely related to the dies; how closely the rifle chamber is cut to specifications plus how closely the sizing die is cut to the sizing die specifications, and then on top those, how much greater the rifle chamber specifications are from the sizing die specifications. When all three actual sizes are very close, that minimizes working the brass and is what gives the greatest cartridge life (IF the many other factors involved with cartridge life are ignored). In this case, they are very far apart and I need to find what manufacturer makes dies that are the closest in size to the chamber in my particular K31. Beyond making a special die based on my rifle's fired cartridges, as has been so kindly pointed out by several of you, Redding makes what I need to get. Thanks!


rl706

[mike in co]

thanks linstrum for the reply.
glad you found the issue and how to resolve the issue.
my use for the redding k31 die is based on the use of norma brass...its just too expensive to over work it.
this is the first issue i have seen on case oal being an issue.

thanks
mike

[Bob S]

I've found Norma brass to be way too soft, and not just in 7.5. Prvi Partizan is only marginally better. Even the much-maligned FNM Lot no. 9001 brass is more durable. After having stretching problems with Norma 7.5 very early in my "Swiss career" (1999), I use my Norma 7.5 brass only for wimpy cast loads in Gew 1889's now, and use reformed 284 for all else. They are virtually indestructable. Of course, YMMV.

Resp'y,
Bob S.

[Linstrum]

I'll be darned, Norma has a fairly good reputation even though that stuff sells for three or four times what it is actually worth. That stuff in 7.62x54R was selling for $1.25 each EMPTY just a few years ago when they were the only ones in the world making Boxer-primed cases in that size. Sellier & Bellot has the absolute crappiest brass I have ever found, though, they do not use the tried-and-true correct alloy of 70% copper 30% zinc. Their brass is very light colored because they use an alloy that is probably 60% copper 40% zinc, or maybe even 50/50 in order to cut costs. I also get shoulder splits on the first firing from their die punch operator overlapping punchings (crescent-shaped cartridge drawing blanks where the missing brass makes a seam right at the shoulder and up into the neck in the finished cartridge) to save even more money outlay on material used, besides using a low-cost inferior alloy. Just plain CHEAP is what that crappy stuff is. The particular batch of Prvi Partizan brass I just got appears to be excellent stuff, I haven't noticed any softness issues with the particular lot I have.

Brass work hardens very quickly, but the operative word here is WORK and it takes getting stretched and then put back into shape a few times in order to harden it up quickly, and that is also what destroys it. The little bit of elasticity that UN-RESIZED brass exhibits when repeatedly fired in the same chamber will eventually harden it up without destroying it quickly, but the limits that must be observed to do that are quite tight. I have one particular Nazi-Germany made, 1940 dated, Berdan-converted-to-Boxer 7.62x53R Finnish (same as the 7.62x54R Russian) cartridge I full-house reloaded 52 times and it got darned hard! The primer pocket gave out and the neck began to get a crack in it, though, so there is a limit on how many times brass can be reloaded and fired in the same chamber. If I had annealed the neck and peened the primer pocket back into to shape I might have been able to get maybe 60 or 70 reloadings from it. That's a bunch!


rl711

[rvpilot76]

Does anyone know if Redding will cut a K31 body die? I've got the Lee collet die set, but I need a body die for the initial sizing of my 284 brass.

Kevin

[Linstrum]

Hi, rvpilot76, I don't think the right folks will see your question here. I can't answer the question since I'm kinda in your shoes, too.

Try starting a new thread over on the Guns & Shooting section, more people will see it there. Good Luck!


rl721

[madsenshooter]

CH4D makes a K31 set, and will sell you the sizing die alone. At, $51 I believe, it isn't cheap, but better than buying a whole set when you already have a seater. Let Dave know you're planning on making your cases from .284 and it'll probably come with a tapered expander ball.

[JSH]

As to dies for the K31. I have been using a set of 30x284 dies for a while now with no ill effects.
I was told by more than a few well meaning individuals that it wouldn't work. Well I went ahead and tried them. All has been well. I suspect the ones who warned me against them just lloked at dimensions on paper rather than hands on experiance.
jeff

[mike in co]

Does anyone know if Redding will cut a K31 body die? I've got the Lee collet die set, but I need a body die for the initial sizing of my 284 brass.

Kevin

you dont need a body die for that...neck up and shoot.....

[jack19512]

I suspect the ones who warned me against them just lloked at dimensions on paper rather than hands on experiance.

I have thought that myself about a lot of things. Many times I have wondered if the person that says this or that won't work has actually tried it themselves. I could name several topics right off but it would just end up in a :takinWiz: contest and eventual thread locked.

[Bob S]

As to dies for the K31. I have been using a set of 30x284 dies for a while now with no ill effects.
I was told by more than a few well meaning individuals that it wouldn't work. Well I went ahead and tried them. All has been well. I suspect the ones who warned me against them just lloked at dimensions on paper rather than hands on experiance.
jeff

Jeff,

I may have been one of the "well-meaning individuals" who told you it won't work. But I actually own a Winchester Model 70 chambered in 30-284; and in the real 3-D world, I can tell you that none of my 6 K31's, 2 K11's 2 96/11's and 2 1911 long rifles will chamber a 30-284 case because the headspace datum is about .015"-.020" longer than the 7.5 chamber. There is obviously less body taper on the 30-284, but the K31 chamber might tolerate that if it were not for the difference in headspace; the 1911 chambers would not. I have not tried to chamber a 30-284 case in either of the 1889's, or the Furter-Olten.

If I may ask, has your carbine ever been checked with 7.5 headspace gauges, or 284 gauges (30-284 and 284 use the same gauges)? What brand are your 30-284 dies, and were they purchased new?

K31's that have been rechambered to 30-284 do exist: see the 10th post in Buckshot's thread. The French could not own the K31 (or any milsurp, I think) in any military chambering; the quick fix to skirt that law was to rechamber them in the 30-284 commercial "wildcat". I saw one of these "French" K31's on this side of the pond many years ago, before K31's were commonplace, but I was not interested enough at that time to note if the carbine was marked to indicate the rechambering.

I suspect that if a guy faced .015-.020 off the base of a 30-284 die (or the shell holder) to get the correct headspace, it may work with a 7.5 K31 ... the result would be similar to the Redding "special K31" dies. I also suspect, but have not tried it (and have no motivation to do so), that a 7.5 x 55 cartridge could be fired in a 30-284 chamber without major discombobulation, if the extractor held the cartridge to the bolt well enough to get a good firing pin strike, or the bullets were jammed into the lands to hold the base of the cartridge against the bolt face at ignition.

If it's working for you, that's great ... but 30-284 will not chamber in any of my 7.5x55 chambers, and "neck up and shoot" 284's doesn't work in my rifles, either. And that's not based on just paper.

Resp'y,
Bob S.

[mike in co]

I have thought that myself about a lot of things. Many times I have wondered if the person that says this or that won't work has actually tried it themselves. I could name several topics right off but it would just end up in a :takinWiz: contest and eventual thread locked.

for the record i BOUGHT lyman, rcbs, lee and redding dies for the 7.5x55....and only the redding is marked k31, all others are marked 7.5x55.......so yes when i talk about the dies,,,i do know what i am talking about...i returned all but the redding...and have since bought the lee collet set. still use the redding only for brass sizing.

mike in co