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K31 bolt question

Discussion in 'Rifle Country' started by Katitmail, Oct 30, 2014.

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  1. chicharrones

    chicharrones needs more ammo

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    I think "rough as a cobb" is a bit harsh and possibly just not describing the feel of the K31 bolt the way I feel it.

    Yes, if I run the bolt slowly on my K31 (or my brother's), I feel all of the bolt turning and cock on opening force when pulling the bolt backwards. To me, that's just a lack of leverage by not being a turn bolt. I feel the same force on Mauser type bolt guns when opening the bolt slowly.

    Where the K31 does smooth out is when running the bolt backward and forward quickly. Kinda the same with a turn bolt gun where if you open the bolt quickly, it feels smoother when unlocking and cocking. To me anyway.

    Firing from prone? My main problem with the K31 is the cocking ring tries to hit me in my glasses. So, I have to move my head while racking that bolt back. I don't have that problem with the same length of pull in a typical turn bolt gun.
     
  2. boom boom
    • Contributing Member

    boom boom Contributing Member

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    My K11 Carbine which shares a similar bolt system to the K31 does not really have a "rough" pull. However, I keep it well lubed. The Schmidt Rubin system does have a very different feel from my other milsurps though because a lot is going on in the bolt versus the relatively simple turnbolt system used by most other bolt actions.

    Besides the Krag and perhaps the first generation Springfields, most of my milsurps are rougher in their bolt action than today's commercial counterparts. CDC milling and modern tolerances for the modern bolt action can affect how 100 year old military technology is rated. Nevertheless, those tolerances are there for a reason and that is functionality under the most trying conditions of all sorts.
     
  3. 35 Whelen

    35 Whelen Member

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    You've got to be kidding. I've owned eight different K-31's and they were all VERY slick. I even modded for High Power competition at which it excelled due to the speed at which the bolt could be operated.

    Prone Rapid targets:

    NovMatchRapidProne.jpg

    P1010075.jpg

    You don't shoot targets such as those above in a competitive environment with a rifle whose action is "rough as a cobb" (sic).


    Don't quite know why you have a grudge against these rifles, but I assure you in the realm of bolt action military rifles, the K-31's were hands-down the finest ever produced.

    35W
     
    Last edited: Nov 3, 2014
  4. tark

    tark Member

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    35Whelen, the best military bolt actions ever produced? I know a few Mauser model 98 lovers that might disagree with you. As for straight pulls, I would rank the Swiss K-31 Swiss as middle of the pack. We will never know, because they were never subjected to the rigors of war.

    The Ross Mk. III was probably worse, it WAS subjected to the rigors of war and it failed miserably, not because it couldn't stand the mud, but because the rear locking lug (it had seven) deformed when rammed against the bolt stop ( sound familiar?) and caused the gun to bind up on the forward stroke of the bolt. The factory discovered this and corrected the problem, but it was too late to save the reputation of the gun.

    I own a MK. III military Ross with a pristine bore. It is the most accurate iron sighted military rifle I have ever owned, I have shot so many sub-minute of angle groups out to five hundred yards with it I have lost count.

    But It isn't a rifle I would take to war.

    Zkf55 you should be beating your head against the wall, because you HAVEN't addressed any of the assertions I put to you;

    The Swiss rifles are accurate and beautifully crafted, but as to their ranking in the world of military rifles, straight pull or otherwise, they don't HAVE a ranking, because they never went to war. They DO appear to have at least one serious flaw, and I wouldn't want to go to war with one.

    And I STILL don't understand what is so hard to understand about your beloved OP-ROD and how it WORKS!!! IT AIN'T ROCKET SCIENCE!!!

    And In case you're wondering, I have been to war. Vietnam, 7 May 68 to 6 May 69

    And I carried an M-14

    Which has an op-rod....... a real op- rod... Sorry, I couldn't resist....
     
  5. 35 Whelen

    35 Whelen Member

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    I bet there's those who would argue the Carcano was best. Or the Arisaka, or the SMLE...still doesn't change things. And since a K-31 will NEVER go to war, what difference does it make now?

    Why do you keep beating the Ross horse to death? We're talking about K-31's.

    And finally, it's not an op-rod, it's called a bolt cam follower, and being a Vietnam combat veteran doesn't make you an expert on the subject of straight pull military rifles.

    35W
     
  6. barnbwt

    barnbwt member

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    I could say something about how you may have damaged your op-rod with rough handling already, but let's just assume that's not the case...

    Have you ever messed with a Steyr M95, before? The Swiss advandced the straight pull technology quite a bit from even that level of refinement, which was, to put it mildly, still lacking at the turn of the century. Put aside the fact a pierced primer can throw the perfectly-intact bolt through your face, the spring-loaded camming of the bolt head was very difficult to overcome when opening, and hard to control when closing, practically forcing the gun to be rammed open and closed (the "ruck-zuck" it was called). Seems cool and super fast until you take it apart and see how delicate the parts involved in carrying that effort are, and how prone to wear the design is. The early Swiss straight pulls were the same gun design under license (IIRC), to be later replaced with the true native designs in 1889, 1911, and 1931. The K11's are reportedly the smoothest (I agree in my very limited experience) owing to how the weaker/longer mid-body bolt lockup and camming geometry worked out, but those guns are markedly more cumbersome to deal with.

    I'd also take issue with comparing the 'smoothness' of any straight pull to a turn bolt; show me a Mauser so "smooth" you can operate it in a straight line? No camming of the bolt head means by definition the action will be smoother, but only because it is doing less. Similarly, when comparing cock on open vs. cock on close actions (yeah, they're really smooth because there is no camming, but you are also fighting a spring on the way down which throws some people off). A Krag is supposed to be the best thing ever, anyways, but only because the action is, again, doing a heck of a lot less with its single lug design.

    The Ross is also hardly a good comparison to use against the K31. Forget the bolt reassembly time-bomb-in-the-field (development could have fixed that) the interrupted thread bolt lug design is simply not particularly happy when unclean. Granted, the K31 wouldn't like that either (again, camming by definition doesn't care for grit, and it'd be an issue even in turn bolts), but a two-lug layout with a more enclosed extractor design likely stands a better chance. The threaded lugs do make for nice, slippery actions when perfectly made and clean (see the very pricey Weatherby vs. Remington 700, and Browning BAR vs. M1 Garand) since the more spread out metal/metal contact area drops contact pressure and thus peak friction when lubricated.

    "P.S. It is pretty obvious what a K-31 op rod is and how it functions, what makes you think it is rocket science?"
    He was talking about fracture mechanics and failure mode analysis, so yeah, pretty much a branch of 'rocket science' that is applicable to lots of things (technically fracture mechanics science got its start in the jet business, but whatever). The Op Rod is probably the weakest part of the K31 design, and was very likely accepted that way because 1) it is not load bearing and thus didn't need to be 'overbuilt' to hold back highly variable chamber/recoil forces, and 2) they didn't have a full understanding of how sharp corners and other features contributed to stress concentrations back then, and had to make a guess at how much something like this part had to be bulked up to make it through a rifle's service life (which they very likely did, in any case)

    With as much money as the Swiss had, and as much affinity for fine firearms as they had, it should be somewhat instructive (if not definitive) that the K31's and 1911's have remained not only popular, but in use for as long as they have.

    "they don't HAVE a ranking, because they never went to war."
    Way to 'win' an argument unfairly; there's lots of reasons the guns never went to war, none of them mechanical. In fact, it may actually be worth noting that the tactics the Swiss had the rifles slated for (defense, rather than offense, on home turf, with well provisioned/disciplined reservists), meant they didn't need to perform as well in hellishly difficult conditions, but that the rifles had to be exceptionally accurate and reliable while clean to maintain that advantage (sniping from a distance). Different tactics, specs, and therefore, different strengths & weaknesses. Yes, "we'll never know" because the Swiss wisely stayed out and got rich instead of destroyed, so get over it and find some other way to compare the platforms than WWII military service in combat.

    TCB
     
  7. barnbwt

    barnbwt member

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    "Why do you keep beating the Ross horse to death? We're talking about K-31's."

    Quite possibly because he knows hardly anyone here or elsewhere has ever seen one of those rifles in person, and can therefore speak from authority on it unquestioned. I must defer to his experience on the Ross having never seen one, so any claims to its superiority must stand. The only area I can assume it inherently suffers is the lug design when grit is present, but that's just a function of surface area (more area means lower contact pressures means smoother when clean & slippery with lubricant. It also means more places for grit to wear on, gall, and bind when dirty)

    I (mostly) kid, but it seems that often in these comparison threads, someone comes along saying their ultra-obscure favorite is the best, and, of course, there's really no way anyone can debate them seeing as only that one person has experience (threads bringing up the H&K P7's awesomeness-in-every-way are notorious about this). They may very well be right, but there's no way it can be discussed let alone debated, so the whole endeavor becomes rather pointless in a purely-printed medium like this. If Tark could email me his Ross for a bit to try out :)D) I would very likely agree with him, but until then, I can't really speak to one side or the other --I can only say the K31 is by far the smoothest/easiest of any straight pull action I've messed with (admittedly, most of them gas-operated), and that combined with their exceptional accuracy and build quality strongly suggests they have a seat in the 'pantheon' of great bolt rifles.

    This is why I try to avoid saying my STGW57 is "better" than an H&K G3 on those guy's threads, since I know hardly anyone has shot one. I simply say it is designed more robustly/simpler in certain ways, and is still an exceptionally accurate and well made gun. Those things don't require personal experience for someone else to appreciate. Although, they are smoother to cock back than an H&K :p

    TCB
     
  8. zfk55

    zfk55 Member

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    Ok, Tark. One last word from me and then the field is yours. Vietnam vet? So am I, but I don't throw it out there as some sort of qualifier.

    The "Op-Rod" is a widely accepted English term for the "riegel", and because the bolt handle isn't attached to the bolt, it is in fact the rod that operates the bolt itself. Yes, Tark. I speak German fluently and am able to read all of the original manuals.

    I'm not inclined to give you lessons in metallurgy but suffice it to say AGAIN!)that those op-rods were not made by Bern or Haemmerli as were the receivers and barrels. They were made by cottage industries and as long as they passed the stringent requirements of Bern, they were accepted. Swiss rifles used by semi-intelligent users did not require op-rod replacements. Present day users like you are the reason for this warning. No Swiss army user "slammed" their bolts in and out of battery. They used properly manufactured GP11 ammunition.

    This odd and unusual situation arose when these rifles began being imported into the US and users began using reloads, often improperly sized. "Hey! It's not going into battery! No problem. Force it. Just slam that bolt forward." Right?

    You can't accomplish that slight difference with a typical rotating bolt with handle attached, but there are some geniuses out there that found it could be slightly forced, so............. that's exactly what they did, and for some it became a matter of course.

    GO BACK, Tark and re-read the post! IE: "These two point on the lug are not inherently weak". So where is the serious flaw?
    If you had even a rudimentary grasp of metallurgy you'd understand what that all means.

    This is an empty-headed field, but for what it's worth............ It's yours, sir.

    P.W. St.Marie
    www.swissproductsllc.com
     
    Last edited: Nov 4, 2014
  9. zfk55

    zfk55 Member

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    And, Tark........ I'll offer an apology for my demeanor. My Son just reminded me of where I am and my vow to remain reasonable during this damned diet.
    I was told I was too old to do it, but I insisted so I'm bound to live with the side effects and status quo until it's over in another week.

    Not an excuse, but a reason. :cool: :uhoh:
     
  10. tark

    tark Member

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    zfk55 ..on a diet..? YOU, TOO! LOL So am I and it sucks. I want my bacon cheeseburgers back. You have my apology also, I guess we get a little heated about our favorite guns sometimes, and my favorite straight pull is the Ross.

    barnbwt seems to be under the impression that I had broken my K-31, such is not the case, my 1911 and my K-31 are both in fine shape. I never made any mention in my posts of "breaking" anything. And I have learned quite a bit from these posts. I have inspected the op-rod on my K-31 and I can see no evidence of deformation or cracking so I think it's good to go.

    I have six boxes of factory loaded Norma 180 GR ammo, which I got for $10 a box in Cedar Falls , Iowa at a Scheel's store. They had been sitting around for years and the store just wanted to get rid of them. It was one of the best ammo deals I ever got. It is the only ammo I shoot in the guns and it is very accurate indeed.

    Now I have a question for you; does the military ammo shoot any better, the same, or worse than the Norma? The stuff is very high priced but it seems to be very high quality.

    Good shooting.
     
  11. tark

    tark Member

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    barnbwt, where are you located? I am retired and I have lots of money, perhaps we could get together in the spring, and I'll SHOW you some Ross Rifles. I have three, including an M-10 Sporter in 280 Ross. (Actually, four, but one of my 280s is in pieces.) My MK III military in .303 is pretty darned accurate, it consistently shoots better groups than my Swiss guns, and I use only Norma 180GR factory ammo in those guns.

    I drive out to California twice a year to see My son, if you live out west I'm sure I could add a few days to yak with a fellow straight pull lover, and maybe even engage in a little friendly shooting competition.
     
  12. zfk55

    zfk55 Member

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    GP11 is used in Swiss matches worldwide and is literally considered match ammunition.
    I've made a very long study of the cartridge and was able to secure nearly 2,000 of the original RUAG GP11 brass back in the 90's.
    My (then) partner and I brought in the first reloadable brass direct from RUAG (SIG) back then offered it to Grafs to handle and market. The response was..
    GP11 brass?? 7.5x55? 1911s and k31s?? No thanks.

    We brought in some 5 or 6,000 cases, sold them within one week and called Grafs back. "GP11? 7.5x55? Absolutely!!"

    The grapevine had gotten to them and after we established a contact for them, they promptly brought in the first 100,000 of many more orders. Shortly thereafter, RUAG slammed the door on that brass and began marketing their own loads and sold Commercially.

    Forgot to mention, GP11 definitely outperforms the Norma. I still have 800 round of Norma here from a long ago purchse of 5 PE57' 5 AMT's and 2,000 round of Norma all bought from Mandalls sometime in the early 80's

    That also began a long term relationship between us and Grafs and we've been a vendor of theirs ever since. Brownells fell in line a year later after watching Graf's sales of our product line. It grew from a retirement business for me into the monster it's become, and I'm fortunate to have a son to take the reins.

    I've spent a lot of years developing loads for all of them, the 96/11, 1911lr, k11, k31 and the zfk55. I've not only duplicated GP11 accuracy, but surpassed is using the same profile projectile, and that would be the Berger 175VLD.

    If I can find the RUAG chart showing what they got into commercially with their cartridge line, I'll post it. It's actually a breakdown of the cartridges by components.
     
  13. zfk55

    zfk55 Member

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    Double post.
     
  14. zfk55

    zfk55 Member

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    I had an agreement at one time on this but the time and term are long past. This is the data on the Swiss RUAG commercial rounds when they stopped selling match brass to the US.

    And Blei means "lead".

    Ruag_zps639500c6.jpg


    Forgot to mention............ RUAG owns Norma.
     
  15. 35 Whelen

    35 Whelen Member

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    I don't have nearly the experience as zfk55, but my findings parallel his; it's all but pointless to handload the 7.5x55 because GP-11 is in and of itself match ammunition. The only thing one might achieve with handloads is the use of an aerodynamically superior bullet.

    35W
     
  16. zfk55

    zfk55 Member

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    Tried a lot of different profiles over the years, but the closest to the GP11 projectile is the Berger VLD 175. The GP11 is a 174gr. Next best I've found is the SMK175, and it's truly a great projectile to work with.
    I have maybe 2,000 of the Bergers here, but.......... I also bought them around 1987 or 89 when they were still very reasonable. The cost per 100 has literally tripled since then. I could never afford to buy them today.

    Not very good shots, probably as good as my eyesight these days but..........

    SMK 175, GP11 and Berger VLD. See the difference in profiles? Its a loooong way from the tips of the GP11 and VLD to the ogive. This is also the reason that the VLD 175 won't work in an AR10 Magazine. simply too long, but the long throat of the 1911 types and the short throat of the k31s accommodate those long noses, and strangely enough, seat depths are the same for both rifles.

    gp11002.jpg
     
  17. tark

    tark Member

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    Well, Ill be damned! Thank you both for the info, I guess I better get some of that stuff. Maybe my K-31 will outshoot my Ross if I feed it the proper ammo!

    I DID try to form some brass from 284 Winchester when I first got my 1911, many years ago. I'll never try that again. The rounds would not feed very well and they didn't always eject. The rim was too small a diameter. The whole project was a disaster and I only did it because I couldn't find Swiss ammo at the time. I fired exactly half the box and still have the other ten sitting in the basement somewhere. I don't think I will ever try to reload again for the two, ever again, even with the proper brass.

    thanks again for the info
     
  18. barnbwt

    barnbwt member

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    I think one other challenge facing the K31 at least, was that one manufacturer of dies (Lee, I think) initially made them to K11 chamber specs and not the K31, which if memory serves, meant that either the shoulder was a bit tight or the bullet was engraving on the lands instead of coming to rest against them as intended. Basically, the result was the ammo wasn't quite right and would be harder to get in and out of the chamber. I believe the subsequent makers have addressed this since so many more K31's are now floating around.

    "I don't think I will ever try to reload again for the two, ever again, even with the proper brass"
    As cheap as GP11 still is, it's not needed. But the cartridge uses the same bullets, primer, powder, and even weight of powder for some loads as 30-06. All while keeping pressures about 10% lower when I last looked into it. Aside from the fact its girth leads to ginormous box magazines, I would have to say 7.5x55 is quite close to an ideal cartridge of the 30-06 power level (which makes a lot of sense in retrospect if you keep in mind the Swiss spent a lot of time and money developing the cartridge from whole cloth over a century ago --it was very close to the 'ideal' solution when concepted, much the same as 9mm Parabellum or 45acp were, and that's why they were selected in the first place. People could do math back then, too ;))

    TCB
     
    Last edited: Nov 4, 2014
  19. zfk55

    zfk55 Member

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    The k31 and it's mates, the 1911, k11, PE57 and the rare (in the US) zfk55 Swiss Sniper Rifle are a rarity in another category. A Military series of rifles designed around a specific cartridge, projectile weight and profile for unusual accuracy and performance in an issue military rifle. The projectile is a 174gr of the VLD type.

    The intent of this cartridge/rifle mating was to accurately hit a human in the kill zone at real range and they performed as intended. Not many military production rifles are capable of doing that as a repetitive whole. The very great majority of these Swiss rifles perform that function flawlessly.

    Are there rifles that outperform it? Of course there are, but none of them are a standard military issue firearm designed around a dedicated production cartridge for that rifle.


    It's not uncommon to see shooters with open sights going out to 1,000 yards with the 1911 and k31.
     
  20. Robert

    Robert Administrator Staff Member

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    We are done here. Too much bickering and non THR behavior to let this live.
     
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