Rethroating a K31 Schmidt-Rubin

[uscra112]

Recently bought a Schmidt-Rubin K31.

Cast the chamber and slugged the bore, and realized that, as is obviously well known on CB.com, this thingy has a throat so short that it hardly deserves the name.

Now, the .308 is widely reported to have a throat shape that is good for accuracy.

Question is, has anybody yet tried running a .308 reamer into a K31 to reform the throat, and what were the results?

[725]

I would not go too fast on a project like this. The K-31 is renown for accuracy and fine Swiss craftsmanship. Live with it for awhile. Learn it's preferences. And then if you get tired of putting a full mag of ammo into one hole at the target, go ahead and put your touch on it.

[JeffinNZ]

Much better to fit a bullet to the rifle than alter the rifle. Once you ream there is no going back and as stated already these rifles SHOOT.

[Ricochet]

No way I'm altering mine! I'll develop loads for it rather than the other way around.

[Linstrum]

After running just one magazine of cartridges through my Schmidt-Ruben I found out just how accurate these rifles are, all the accolades are quite deserved! I wouldn't mess with mine!


rl435

[johnly]

I have a scout mount on my K-31 and it's a MOA shooter if I do my part.

If your rifle has a short throat like mine, I'd suggest using 311291 or 311041 designs that were developed for the 30-30.

John

[beemer]

I have reamed the throat of a 30-30 and a 308 that has a NATO target barrel. Both had no taper in the throat, it helped the 30-30. I don't know if it helped the 308 as I haven't shot it much yet but It didn't seem to hurt either. I do know that both rifles are easier to deal with as far as seating depth and boolit selection. I would do it again but one has to remember that it can't be put back and you are stuck with the results.

I have 2 of the Swiss K31 rifles and thought about reaming the throat of one. The Clymer throat reamer I used has a pilot dia. of .299 and will not enter the bore of the Swiss. You would have to be sure to have right reamer with the proper pilot dia. If the reamer had fit I would have probably done it. It was an interesting project

beemer

[uscra112]

Thanks, guys ! I was in quite a quandry, having only Loverin-style molds for cal.30.

I have read about reaming the .30-30, in an article by C.E. Harris in the Rifleman. That's what put me onto the idea of reaming the K31.

But if 311291 will work, I'll mess with that first. I'll have to buy the mold - I don't have one. It looks like it'll have a goodly bit of the nose up the bore when it's seated - but how big does the nose cast, say, in wheelweights, or linotype? This K-31's bore slugs at .299. Not exactly roomy in there.

Now, I just ordered a 311332 for my "new to me" Springfield, which has a 2-groove barrel. It has a longish bore-rider nose and a shortish body. It's pretty near the ideal boolit for the 2-groove barrels, according to Col. Harrison. Maybe that'll work in the K31, too, even though there's less land area in the bore.

I'm certainly not sorry I bought this K-31 - I've NEVER gotten a mil-surp that was in such excellent condition, (except for my 71/84 Mauser, which I swear may never have been fired!). And at the asking prices, I may just go buy another just 'cause it's such a bargain! Or should I go for an 1889 instead? Call me a doofus, but I actually LIKE patching boolits.

[jhrosier]

FWIW, I've shot the 31141 in my K31. It fits the short throat with no problem and gave good accuracy. It is easily the most versatile design mould that I own and has shot very well in many different cartridges.

Jack

[johnly]

I have a Lee 6 cavity 311041 mold that has yet to be used. Want to borrow it?

John





Thanks, guys ! I was in quite a quandry, having only Loverin-style molds for cal.30.

I have read about reaming the .30-30, in an article by C.E. Harris in the Rifleman. That's what put me onto the idea of reaming the K31.

But if 311291 will work, I'll mess with that first. I'll have to buy the mold - I don't have one. It looks like it'll have a goodly bit of the nose up the bore when it's seated - but how big does the nose cast, say, in wheelweights, or linotype? This K-31's bore slugs at .299. Not exactly roomy in there.

Now, I just ordered a 311332 for my "new to me" Springfield, which has a 2-groove barrel. It has a longish bore-rider nose and a shortish body. It's pretty near the ideal boolit for the 2-groove barrels, according to Col. Harrison. Maybe that'll work in the K31, too, even though there's less land area in the bore.

I'm certainly not sorry I bought this K-31 - I've NEVER gotten a mil-surp that was in such excellent condition, (except for my 71/84 Mauser, which I swear may never have been fired!). And at the asking prices, I may just go buy another just 'cause it's such a bargain! Or should I go for an 1889 instead? Call me a doofus, but I actually LIKE patching boolits.

[725]

There is a group buy, waiting for delivery, of a boolit specifically designed for the K-31. It was listed under "custom 165" or some such. Perhaps, those specs could be useful for you if you wanted to order a custom mould. from someplace like Old West Moulds. I'll root around and see if I can find the original posting.

Ok. Click the search above and look for "custom 165 silouete". Should give you a bunch of info & contact sources.

[JDL]

I've had excellent results with Lyman 311466!

[garandsrus]

USCRA,

The RCBS 165-Sil shoots great in my K-31. I have one of the 6 cavity group buy molds. I would be willing to send you some boolits to try...

John

[RU shooter]

If you want to try an economical route get one of the Lee 30 cal moulds like the 160 -200 gr. They usually have a nose around.298-.299 and seem to fit quite well in the K31 In my shooting with the Swiss I had my best luck with the Lee 312-155 ,yes you need to seat it a little deeper in the case but shot the best for me The Lee 309-160 was a close second both sized to.311 Yes I know thats big for the K31 but it consistantly shot the best at that size,cant argue with success!

Tim

[Ricochet]

Nominal bore diameter of the K-31 is said to be .296", and that's what I measured with mine, with .308" grooves. I got a Lee 200 grain mould, all excited that I'd get .298" bore riders like I've seen folks complain about on here. Mine cast .302x.304" bore riders. If I cast 'em soft I can slam 'em into the barrel, but I have to slam the handle again with the heel of my hand half the time to get it locked and that hurts. That would be a perfect boolit with an appropriately skinny nose. Anything fatter than about .298" is pretty fat for an unworn K-31 throat IMO. I have one of the Group Buy #311291 moulds but have yet to try it out. I fear it may be too fat and have to be relegated to my standard .30s.

[Boz330]

Ditto what Rick said. I would have gotten in on the group buy but my K31 lands are .2955. I'd like to see a 311299 with the smaller nose. The standard won't even begin to start in mine. I've got a buddy who is supposed to make me a 2 step size die to try.

Bob

[Bob S]

Ricochet:

That's amazing, it sounds like you got a 309 Lee mould that might actually fit a US cal .30. All of my Lee 309 moulds (160 grain, 180 grain and 200 grain) cast .298-.299 on the nose and have been worthless in US .30 rifles, but the moulds are all at least 20 years old. Maybe Lee is finally getting their act together.

All:

One thing that can said about the K31's that came into this country up to about 4 years ago, at least, is that they were fired very little. That's based on bore-scoping several dozen that came by my place for "consultation" when the prices really dropped way down about 2001. Shoot about 1000 rounds of GP11, or equivalent jacketed bullet handloads, through one and you'll be amazed what the rifle will accept as far as cast bullets are concerned. My first K31 was purchased in 1999 and I put over 3000 rounds of jacketed handloads through it in two+ seasons of XC High Power ... it will chamber a 311299 with the GC at the base of the neck, lightly engraved, and will extract a loaded cartridge without debulleting and without excess effort.

The remaining 5 K31's that I currently own that are still in 7.5x55 have not been fired that much. None of them will accept a "regular" 311291, or even my old Ideal 311291U without deep-seating. (the 311291U shoots wonderful groups out of all of my 1911-types, though). All of them will accept the old Lee 160 grain and 180 grain round nose 309 bullets; the 200 grain needs to be deep-seated (but that one works wonderfully in the 1911-types, too). The bullet that works universally in all of my 7.5 K31s is the Lee C312-155-2R, the "SKS bullet". The Lyman 311672 is a close second. The Lee bullet when seated with the GC at the base of the neck will lightly engrave and will extract without debulleting or excess force.

YMMV .....

Resp'y,
Bob S.

[KCSO]

I just went with the Lee bullets that didn't fit in my 30 cal rifles and was plumb happy. I have a St Marie scope mount on mine and it has shot the single best cast bullet group I have ever fired with a service rifle. Under 1" at 100 yards! I wouldn't mess with the throat for all the tea in China, even if India has more tea!

[Ken O]

A 311041 works real good in my K31s. Also the jacketed Rem 165 PSP sold in bulk by Midway are real hammers. Midway has had sales on these and were real cheap.

[primersp]

A 311041 works real good in my K31s. Also the jacketed Rem 165 PSP sold in bulk by Midway are real hammers. Midway has had sales on these and were real cheap.

hello

with this cast bullet wich long of the cartrige it must seat far in the case
i try one but impossible to close the bolt ,i choose the 311466 who
works well
here due the legislation almost the military rifle k31 or mas 36
are in 30-284 and the reaming is often "special" my reload ammo
once fire don't load in my buddy rifle.
have a nice day
ANDRE

[Ricochet]

Andre, over here many people have used 30-284 dies to reload 7.5 Swiss cases. They work pretty much as a neck sizer, I think, since the 30-284 has a more steeply angled and forward placed shoulder and a body with less taper. For my K-31 I've been using a Lee collet neck sizer, and it would work for your 30-284 also. I have yet to full length size any cases for the K-31. Some are on their eighth loading and close easily into the chamber. I find many bullets have to be seated very deeply into the case to allow easy bolt closing, as you do.

I've just gotten a G.11 and a 96/11, and as I still have some Prvi Partizan factory loads I believe I'll start these rifles with them and keep fired cases segregated so I can neck size them. I've never segregated cases with other calibers like 8x57 and 7.62x54R for which I own multiple rifles.

[happyret65]

I have 2 K31's and 1 96/11 (K11 on order). I found out the hard way that you had better seperate the cases. I tired to put some K31 brass in to my 96/11, what a mess, had to punch out the brass as they were oversized. The 96/11 I have has a smaller chamber than the K31. Personally once you've fired the 96/11, you leave the K31 in the safe, what a great rifle.

Also, a friend and I bought a reamer to open up the K31 throat. Worked like a charm no more pushing the bullet too deep in the brass (any 30 cal mould will work now) and the reamer was about $95.00.

[Bob S]

Also, a friend and I bought a reamer to open up the K31 throat. Worked like a charm

What size pilot did you use with that throater in the K31? No regular cal .30 pilot is going to fit in any of my K31s.

Resp'y,
Bob S.

[Ricochet]

Yeah, I tried the fired cases from my K-31 in my 96/11 and G11. The fatter shoulder sticks tightly, more than 1/4" away from closing.

The K-31's chambering and throating are different from the older rifles. Chambering's more tolerant of dirt and stuff on the cases, throat's specifically tailored to the GP-11's bullet. The older ones had to be able to handle GP-90 and its successors as well. Makes them far easier to fit a cast boolit into, but still there's no way I'd EVER rethroat my K-31. I'll load for it, not modify it to fit my loads. It is what it is.

[MtGun44]

I'm with Richochet, no way I'd modify any of my K31s. Adjust your ammo
to the gun. The gun is very accurate, if you mess with it, who knows what
it will do. Why risk ruining a great rifle?

Bill

[madsenshooter]

I think I have a cast boolit that will work very well in the K31. It's the Eagan 30G. It's a tapered nose pour design for those of you who don't know Don's designs. It casts 190gr in linotype. I have a shortened version here that is 1.15" long vs the original 1.25" length of the 30G and weighs 194gr cast in the alloy I'm using. I can load it to an OAL of 2.927" in the 7.5x55. The rifling is engraving the 2 uppermost bands and the base of the bullet is even with the shoulder of the case. The bolt on my particular K31 closes easy at this point. Hornady BTSPs have to be seated fully to the cannelure in the same rifle. I haven't shot any yet, but I'm anticipating excellent results from both it and the full length version. I own the cherry and the full length version with longer nose and smaller meplat will be available soon. This isn't the marketing section of this forum, so if anyone has any questions or would like more pics, contact me, you can email me on the forum, or use the red Y above to IM me.