Swiss K31: Stunning

ptosis

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Years ago I disassembled 10 rounds of GP11. Measured bullet weight, ogive, powder charge. case, overall weight, neck concentricity etc.

For mass produced ammo, it's darn near a hand load in consistency. At least the lot that I measured. Pretty impressive as it's typically referred to as "surplus".
Indeed, the standard deviation of muzzle velocity of 1990s production GP11 is typically between 4 and 4.5 m/s (13-15 fps), depending on the batch, and with a match barrel it typically stays within the 10 ring of ISSF target at 300 m (10 cm); in Switzerland the ammo is routinely used for 300 m CISM/ISSF standard rifle competition.

For a bulk military issue cartridge, GP11 is insanely well done.

BTW, RUAG restarted the GP11 production lines in 2017, after more than 20 years break. This new production is just as good as the old one (and, regretfully, it is still berdan-primed).
 
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Spicerack

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Finally added one to my safe. 1943 serial number. Now to find some ammo!
20220403_161655.jpg
 

sandwarrior

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Finally added one to my safe. 1943 serial number. Now to find some ammo!
View attachment 7842534
Haven't seen any real GP-11 for years. Your best bet is to reload. As mentioned by Pierre, 175 SMK's work well. Graf's has PRVI bullets that match your needs. If not quite as accurate, they do have a great BC.

If you do not have reloading capabilities find someone who does, and work with them to get rounds loaded.
 
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Ledzep

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    I've also gotten away with resizing .284 win brass. It matches the body diameter, and so far I've had decent success with the rebated rim working with my rifles. It's not as solid as the full diameter rim on dedicated brass, but it works and is often easier to find.
     

    Calfed

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    Finally added one to my safe. 1943 serial number. Now to find some ammo!
    View attachment 7842534
    Beautiful rifle!

    SG Ammo has some Prvi 7.5 Swiss in stock.


    Edit:
    Ooops...just noticed your subsequent post.
     

    Winchester M70 Van Orden

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    Good evening, Chancellor,

    A very well description of your experience ! 🙂
    And welcome to the Schmidt-Rubin-Carbine and Long Rifle-Family 😀

    Regards from the Alps
     

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    Davo308

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    Wish I could find some berger 174s so I could pull some gp11 down and seat them in the gp11 case.

    I don't want to spend 35 bucks for 20 ppu rounds.

    Also heard berger stopped making those bullets
     

    kujuak

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    Wish I could find some berger 174s so I could pull some gp11 down and seat them in the gp11 case.

    I don't want to spend 35 bucks for 20 ppu rounds.

    Also heard berger stopped making those bullets
    Berger 175VLD target bullet is bullet I think closely matched GP11 bullet. It has been discontinued. I have a few boxes but could not rationalize searching for more old stock given lack of long term availability.Under 300yds no particular advantage for these expensive bullets so I'm saving them for playing at long distance. Luckily I was able to get a bunch of GP11 on sale back in the day at $200/case.Working on shooting it up before it goes bad. One of my Swiss beauties.
    BkdSjir.jpg
     

    Calfed

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    Wish I could find some berger 174s so I could pull some gp11 down and seat them in the gp11 case.

    I don't want to spend 35 bucks for 20 ppu rounds.

    Also heard berger stopped making those bullets
    I'm not sure how much improvement you could get by replacing the GP 11 projectile.

    7L3gBRN.jpg


    These are 175 gr Nosler CC, Sierra MK, Barnes Match Burner, and the GP11 projectiles. I think the Barnes MB is similar to the Berger
     

    Calfed

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    Nosler has a line of Reduced Drag Factor "RDF" bullets out. I picked up some of the 175 gr .308 RDF's. Very similar to the Barnes Match Burners.

    I noticed the meplat is much smaller and more uniform than other .308 175 gr match bullets.

    Various 175 gr .308 bullets...

    PUEQE10.jpg

    Sierra MK, Nosler Custom Comp, Barnes MB, Nosler RDF
     
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    Davo308

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    I'm not sure how much improvement you could get by replacing the GP 11 projectile.

    7L3gBRN.jpg


    These are 175 gr Nosler CC, Sierra MK, Barnes Match Burner, and the GP11 projectiles. I think the Barnes MB is similar to the Berger

    The problem is with the GP11 bullet...the local ranges hit it with a magnet and declare its steel core.

    When I point out its a cupro nickel jacket and that it's magnetic their eyes roll back.

    My favorite is when they say drive the 1 1/2 hour drive to the range so we can tell you you can't shoot GP11.
     
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    Calfed

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    The problem is with the GP11 bullet...the local ranges hit it with a magnet and declare its steel core.

    When I point out its a cupro nickel jacket and that it's magnetic their eyes roll back.

    My favorite is when they say drive the 1 1/2 hour drive to the range so we can tell you you can't shoot GP11.
    That is a good point. In the absence of Berger 175 VLD's, I think the Barnes and Nosler RDF's are as close as you can probably get to the GP 11 projectile.
     
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    ptosis

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    The original GP11 projectile has a G7 BC of 0.274; that's what one should aim for to reproduce the original external ballistics. If my memory is good, Hornady has something 175grain-ish with a very similar BC.

    This said, the projectile has evolved over the years (I could never find any documentation, but the ballistic tables for the K31, the Stgw 57 and Ruag doppler data are not exactly the same), and the K31 iron sights elevation is a little bit too pessimistic for the recent production ammo.
     
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    Tempest 455

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    I've shot GP11 out to 1K many times. Being F class person, I would not call it super accurate.
    However, it's pretty killer at 600 yards for surplus with irons.
     

    Davo308

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    I've shot GP11 out to 1K many times. Being F class person, I would not call it super accurate.
    However, it's pretty killer at 600 yards for surplus with irons.

    I'm hoping with a good target scope I can get out to 800.

    Figure a projectile that stays supersonic to 1k will have an easier time at 600/800 yards.

    It's one reason I'm looking at the 169 grain smk, which is intended to increase tran sonic performance of .308 bullets.

     
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    Davo308

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    I'm hoping with a good target scope I can get out to 800.

    Figure a projectile that stays supersonic to 1k will have an easier time at 600/800 yards.

    It's one reason I'm looking at the 169 grain smk, which is intended to increase tran sonic performance of .308 bullets.



    Also I have added about 3 lbs of weight to the K31(all reversible) and a compensator.

    I'm hoping this cuts down on stresses to the 72 year old stock.

    The scope is Frank approved...

     
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    Calfed

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    Also I have added about 3 lbs of weight to the K31(all reversible) and a compensator.

    I'm hoping this cuts down on stresses to the 72 year old stock.

    The scope is Frank approved...

    That is a nice scope. A few years ago Natches was blowing them out and I grabbed myself a few. Nice glass, repeatable adjustments, made in Japan.
     
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    Davo308

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    That is a nice scope. A few years ago Natches was blowing them out and I grabbed myself a few. Nice glass, repeatable adjustments, made in Japan.

    I like how its mil/mil and I picked up a new in box for 200.

    Just wondering if the lack of parallax is bad and would like another 10 moa adjustment range.

    I found some links to making a defacto zero stop as well.

    As it is it should get me to 800 maxed out but realistically 600 meters/650 yards will be as far as I plan to shoot.
     
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    Calfed

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    I wondered about the lack of parallax adjustment, but note that many scopes in that power range do not have that feature
     

    Calfed

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    Swiss Products has long made a clamp-on Scope mount for the K31. The problem is that it mounts the scope to the right side of the bore axis. They have now alleviated that problem with an add-on that places the scope over the bore axis.

     

    ptosis

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    Swiss Products has long made a clamp-on Scope mount for the K31. The problem is that it mounts the scope to the right side of the bore axis. They have now alleviated that problem with an add-on that places the scope over the bore axis.

    Looks good, thank you!

    This said, judging by the photos, it should be coming with a ~50mm cheek riser in the kit.
     
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    TorF

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    Has anyone tried the Swissproducts sidemount rail for left side of the receiver?
    This mount will place the scope in the same position as on a Garand Sniper.
    With a Garand sniper cheekrest and this sidemount, and with a scope in low rings, I think this would be a very good compromise. No need to move head away from the stock to avoid the bolt hitting the head during reloading.
    Skjermbilde 2022-04-19 124312.png
     
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    M77

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    Shot a Service Optic match a few months ago with the K31, man its such a sweet rifle to run. I will end up using a better sling for unsupported shooting but I was just happy to shoot the thing.
     

    Winchester M70 Van Orden

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    Berger 175VLD target bullet is bullet I think closely matched GP11 bullet. It has been discontinued. I have a few boxes but could not rationalize searching for more old stock given lack of long term availability.Under 300yds no particular advantage for these expensive bullets so I'm saving them for playing at long distance. Luckily I was able to get a bunch of GP11 on sale back in the day at $200/case.Working on shooting it up before it goes bad. One of my Swiss beauties.
    BkdSjir.jpg

    A beautiful looking :)

    A Leupold Scope. Which magnification and reticle do you use, If I may ask ?

    Comparison between the GP 11 and newer bullets: thats my impression too. At distances until 300 yards that seems to be the usual experience. The ranges above 300 yards are another chapter. Fine choice of bullets you have in the States... . ;) And you may reload our GP 11-Cases. That makes the reloading really easier. Here that is forbidden for civilian use.. .

    A bunch of GP 11 on sale: that sounds good. Which year of production is it ?
    (I hope, you all know that the GP from the production-year 2016 and newer has caused serious trouble in our 3 Service-Rifles Assault-gun 57 resp. Stgw 57, Karabiner K31 and Long-Rifle G11 ?) In contrast to the older productions.. . A CH-Gunsmith warned me explicitly recently.
     

    ptosis

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    That makes the reloading really easier. Here that is forbidden for civilian use.. .
    Shooting a k31 is allright, but reloading GP11 brass is not? Here = where?

    (I hope, you all know that the GP from the production-year 2016 and newer has caused serious trouble in our 3 Service-Rifles Assault-gun 57 resp. Stgw 57, Karabiner K31 and Long-Rifle G11 ?) In contrast to the older productions.. . A CH-Gunsmith warned me explicitly recently.
    Hearsay. Ruag and the army have done a very, very serious study based on these claims, and have factually refuted all claims in that sense (which, by the way, perfectly matches the results of my own tests of old vs. new production -- no perceptible difference in precision or muzzle velocity SD).

    The only confirmed problems involved standard/free carbines chambered in 7.5, and aftermarket heavy barrels for the Stgw.57 (did I hear G&E?), because, in a pursuit of ultimate precision, chambers were off-spec (done to the size of the production brass rather than to the CIP min. size).

    Any ordnance barrel shoots the new GP11 just fine.