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  1. #1
    Join Date
    Dec 1969
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    Anchorage, Alaska
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    240

    Default 7.5x53.5 Swiss reloading

    Howdy, I'm about to buy a carbine in this caliber and will need to make up cartridges for it. Anyone out there
    make up loads I could learn from. Can the 7.5x55 brass just be shortened or what is the procedure? How about bullets, a different diameter from the little I've been able to come up with, .304 if I've got that correct. Sure would appreciate any help. Thanks in advance and regards, Guns
    I Collect, therefore I am.

  2. #2
    Join Date
    Sep 2008
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    115

    Default

    I played with the GP 90/23 round a while back for the G-89 and basically here are the shorthands:

    1- You can make suitable brass by shortening GP-11 brass.

    2- 7.5x55 dies will work fine, but there is a specific special order RCBS die set for the GP-90 (1890 that is).

    3- Original GP-90/23 ammo uses a .307" slightly tapered RN bullet. .308" in the 180-220 grs range is fine (GP 90/23 is 190 grs as I recall)

    4- The original 1889 and 1890 projectiles are swaged hardened lead, heeled PP bullets about .319-.320 " in diameter with the patch.

    5- Because of that, the throat is cavernous and you'll get useless results (and some gas blowby) unless you support the neck by means of a grease ring.

    PM me if you're interested in some load info.

    Cheers,

    JH

  3. #3
    Join Date
    Sep 2008
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    115

    Default

    Here are a couple of pictures to illustrate the above information. The 3 cartridges are (Left to Right) GP-11 duplicate loaded for K-31, GP-90/23 duplicate with 220 grs bullet and 180 grs bullet. Close up on neck and shoulder area for comparison. There is a fired and recovered GP90/23 projectile, side and rear views (note the clover appearance of the back due to 3-groove rifling in the G-89), unfired unpatched and PP GP-90 projectiles showing the steel capped nose and heeled design, side and rear views, and finally a side-by side comparison of unfired empty cases GP-11 and GP-90 profiles. There is also a side-by-side comparison between a genuine GP-90/23 and my duplicate. RCBS P/N for the GP90 dies included for the real maniacs. GP-11 dies will work fine at the expense of a little work-up of the brass at the shoulder-neck area.

    Enjoy!

    JH
    Attached Thumbnails Attached Thumbnails GP90_23 bullet2.jpg   GP11_90_23 comp2.jpg   GP90_23 bullet1.jpg   GP11_90_23 comp1.jpg   GP90-4.jpg   GP90-3.jpg  

    GP90-1.jpg   GP90-2.jpg   GP90_23 dup1.jpg  

  4. #4
    Join Date
    Dec 1969
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    Anchorage, Alaska
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    Default

    Hello JH, These are fantastic pictures and great information. I have a much better idea how the paper patch worked, and how you made the cartridges. Thanks again for all your help.
    I have made several attempts to post pictures of the Swiss Mannlicher 93 carbine, with no luck. I've tried both my wife's and my computer, and going over the suggestions by the
    gunboard help, but when I attempt upload, it makes the motions like it is doing it, then never appears in the downloaded files box. It just stays empty. Never have been much of a computer whiz.
    I'll let you know when I've made up the cartridges and how they work in the carbine. Best regards, Guns
    I Collect, therefore I am.

  5. #5

    Default

    Mezigot;
    I have to hand it to you, you know your stuff when it comes to duplicating the GP 90 round - I've gained some good advice re your grease band around the neck, as well, and may also try it through my K 31.

    I have a Baenziger St.Gallen retailed Swiss Martini Schuetzen rifle with an early Hammerli barrel chambered for the GP 90 round that I have been reluctant to shoot with jacketed projectiles because of the original bullet being paper-patched lead.

    I was mainly concerned about rising pressures and ultimate barrel throat wear using jacketed bullets.

    Can you suggest an accurate low-pressure load? I was thinking of a load that would run around 1900 FPS with a 180gn RNFB bullet, or alternatively, a cast 190gn GC at around 1300-1500 FPS. Suggestions welcomed...!

    Cheers,

    Gingerbeer.

  6. #6
    Join Date
    Sep 2008
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    115

    Default

    Gingerbeer:

    Thanks for your kind words, glad to hear the information is useful. Regarding the K-31 use, the neck is very well supported so you don't need the grease band. All loads of the GP-11 except the few last years of production had a small ring of a waxy grease at the junction of the case mouth and the bullet. My experience has been that it makes cleaning easier by preventing jacket metal fouling build up. I even got my hands on the tool to apply the grease ring, but unfortunately, no luck (so far) on getting the grease.

    If you are using a lead core copper jacketed bullet, I would not be too concerned about throat wear. The real offenders are mainly large loads of slow powders, gas blowby with improperly hardened and/or sized cast bullets, steel jacketed bullets or, with the deep 3-groove design of the G-89 barrel, solid bullets. In addition, you are not likely to go through 1000's of rounds in your shuetzen rifle per year.

    The GP-90/23 duplicates I came up with is fairly low pressure, with velocities estimated to be in the 2000 fps range (I have not chronographed them yet). Certainly well within pressure specifications for the G-89 and they do calibrate fairly well with the sights. I have a friend that has played with casts bullets in the 1400 fps range with decent short range (100 yds) results. I tend to be somewhat nervous about very low density loads, even of a fast powder, and fillers in the GP-90 case makes me cringe (not to mention their effects on throat wear). I'll PM you some load details.

    Cheers,

    JH

  7. #7

    Default

    Much appreciated for your help and advice, JH.

    Will look forward to some suggested loads when you find time.

    Regards,

    Gingerbeer.

  8. #8
    Join Date
    Sep 2008
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    115

    Default

    For those interested, I have taken a few measurements on the GP 90/03 case and bullets these are average of multiple measurements:

    Case neck outer diameter above shoulder: 8.84 mm

    Case neck outer diameter below crimp: 8.72 mm

    Case neck outer diameter at crimp: 8.52 mm

    Corresponding ID: 7.80 mm

    GP90 bullet. Left measurement is the naked bullet, right is with the papper patch in place.

    Heel OD: 7.68 mm; 7.82 mm

    Shank above heel OD: 8.05 mm; 8.21 mm

    At junction of nose steel cap OD: 7.90 mm; 8.04 mm

    Length of heel: 5.90 mm; 5.80 mm

    Bullet OAL: 29.62 mm; 29.59 mm

    This confirms that a normal (read GP-11) set of die could be used to resize the GP90/03 round, but a slighly larger expander plug (say .310) might be useful in avoiding damages to the PP while loading.

    Enjoy,

    JH

  9. #9
    Join Date
    Dec 1969
    Location
    Anchorage, Alaska
    Posts
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    Default

    Excellent information JH, thanks for your efforts. I finally got some Magnum primers and I plan to start trimming virgin 7.5x55 down to the 53.5 today. The Swissrifle.com page show the cartridge case length as 2.106 inches. I slug mic'ed the Mannlicher bore at .308/.304, so that should work perfectly with the .308 bullets. Hope to be able to try the carbine out on Sunday. You have been a great help. Regards, Guns
    I Collect, therefore I am.

  10. #10
    Join Date
    Sep 2008
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    115

    Default

    Guns,

    If you're trying to duplicate the GP 90/23, you should trim your brass to 54.5 mm instead of 53.5 mm. This will minimize the risk of neck collapse and give you a better centering with the grease band.

    Regards,

    JH

  11. #11

    Default

    I thought I would share my experience shooting a cast bullet load following suggestions and normal cautionary advice by Mezigot to use in my 7.5mm Swiss Martini. Given that this rifle was manufactured in the early 1890's with three-groove rifling, I took it for granted that the case length was the early 53mm. Actually by chance - doing a chamber cast - I found that some enterprising gunsmith had ran a neck reamer into the chamber and lengthened the overall length to 55mm, as the chamber cast picked up a very slight line indicating the old 53mm length.

    I mention this only to highlight the possibility that perhaps some of the original S-R '89's could also be lengthened to take the later GP cartridges, but hopefully not the more modern GP 11.

    In one way this was good news for me as I then did not have to trim my 55mm cases back to 53mm. I should mention here that since purchasing this Martini I have established that the Swiss Martini action will withstand greater pressures than the S-R Model 1889, but be that as it may, I would not want to test that theory using regular GP 11 ammo through it!!!

    I also found, like Mezigot commented on, that these early 3-groove barrels have a very long leed, or throat, before the rifling was reached. In my situation, this meant seating a 180gn gas-check cast bullet in the case only to the depth of covering the gas-check. Even then, there was about a sixteenth of an inch jump before it touched the lands.

    My load was 34gns of 3031, and although a magnum primer was recommended for this load, my cases were original Berdan which necessitated standard RWS primers.

    At 100 yards, off the rest, and after sighting shots to get on the target, I shot two 5-shot groups at 1.5" each group, with original open sights, in a light drizzle (no wind). Primer expansion was normal ,and no blackening down the outside of the cases was apparent, which suggests to me that 3031 should be a suitable powder for gas-check lead bullets with the above powder load.

    I caution anyone considering using the above load NOT to exceed 34gns of 3031 and a 180gn Lyman No.2 bullet weight as a starting load, or substitute any other powder, or heavier bullet weight. This load was a suitable starting load for the Swiss Martini and should be used with caution in the earlier '89 models.

    Given that my Swiss Martini has a 1 in 10.6" twist, which the same twist for ALL Swiss straight-pulls, the above load should be suitable in the Model 11 and K 31 rifles providing that the bullet is seated in the case to suit the throat, with the proviso that if the base of the bullet drops more than the depth of the gas-check below the neck, accuracy will suffer as a result of gas-cutting on the sides of the projectile. This means that the projectile must have a nose bearing surface that rests on the lands, if the throat is short, like the K 31.

    I hope the above info encourages owners of Model 1889 rifles to load up some lead projectiles and get them shooting again!!!

    Gingerbeer

  12. #12
    Join Date
    Dec 1969
    Location
    Mountain View, California - Silicon Valley
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    401

    Default

    Mezigot, Gingerbeer, GunsGunsGuns, et al. Thanks for the great topic! I've got a Gewehr 1889, a 93 Repetierkarabiner, and a 97 Kadettengewehr I have been dragging my feet about getting out and shooting, but this is all great information and I am glad this post got started, G3, and thanks to JH & Gingerbeer for such good information. I would like some confirmation from any of you that the information I read in Bewaffnung und Ausreustung der Schweitzer Armee seit 1817 Volume 4, that all three of the above are compatible with GP 90, 90/03 and 90/23 is correct, even though a lower velocity is listed for the Kadettengewehr . Also I want to be sure I am clear on the grease ring. Do I understand correctly that its purpose is to center the case neck in the chamber? but how the dickens do you apply it so neatly and what are you using for grease? I'd like to load 220 gr. Hornady jacketed RNFB .308 bullets, as I have a lot of them on hand, and plenty of brass, LR primers, magnum & std. and a variety of powders. The Hornady bullet does not have an exposed core as in your picture. The jacket covers the flat base completely so there would be no obturation, and maybe the issue is insignificant. But just to be sure, is that any reason not to use them? JH, I'd also like to PM you for some suggested starting loads. I've been shooting my 96/11 on up through K 31's with handloads for years and had no problems,and I'd sure hate to damage these old treasures out of ignorance.
    Best regards, Kari
    Best regards,
    Kari Prager

    "Schiessen und Treffen, nicht Schiessen und Knallen."
    "Meine Waffe", Oberstlieut. Mariotti, Schweizerische Armee, 1918

  13. #13

    Default

    Hi Kari,

    Mezigot without doubt has the answer to the "grease ring" so I will not steal his thunder. I can give you good accurate loads for the K.31 and the Swiss 7.5mm Martini, but will leave the M 89 loads to Mezigot and his mate who are the experts with loads for the 1889 rifle.
    Congratulations on obtaining the '93 and the Cadet rifle, two very scarce pieces, without doubt.
    Good luck with your collecting and shooting!
    Cheers,
    Gingerbeer.

  14. #14
    Join Date
    Sep 2008
    Posts
    115

    Default

    Gingerbeer,

    Expert, expert, you are too kind. Just got something that works decently. There is some potential for fine-tuning. I will definitely have to chronograph the loads to see how they are doing, as soon as the snow melts out of the way though.

    Kari,

    The picture of the bullet base you is is an original (shot) 1923 bullet from the GP-90/23 cartridge. The plain base is not an issue, and if you work out the surface area of the 3-groove barrel vs that of the base of the Hornady 220 grainers, you will see that they match nicely (slight amount of compression). PM sent Re loads.

    Cheers,

    JH

  15. #15
    Join Date
    Mar 2010
    Posts
    1

    Default

    Dear Mezigot
    I tried to buy in Spain this RCBS dies in the main RCBS supplier in Spain and He said me that this costs 300€ (aprox. 375$)and six month to expect.
    Please can you indicate me, where youbought this RCBS dies for the K11 (7,5x53 Swiss)?.
    This is for contacting with your supplier and buying its.
    Thanks in advanced from Madrid (Spain).
    I attach a link where we organize I postal league (very similar at Swiss postal league) and we have a blog exclusive for a K31 Rubin:

    http://server4.foros.net/index2.php?mforum=SWISSK31

    Frank

  16. #16
    Join Date
    Sep 2008
    Posts
    115

    Default

    Dear Frank,

    If you are shooting a K11, it will handle best the GP11 i.e. 7,5x55, not the GP(18)90 , i.e. 7,5x53,5 which is what the die set pictured is for. I did order them a long time ago from a small swiss gunshop for 90 CHF. They are indeed a special order and that gun shop had a small series made to bring the cost down. I got their nearly last set. Note that it is not absolutely needed to reload GP89, GP90 and GP90/23, a normal 7,5x55 mm die set will do, just a small difference at the radius of the shoulder angle, and, of course, a larger expander if you plan to load the PP bullets. For my G11, K11 and K31s, I use the RCBS competition die set #38601. Works like a charm, and should be significantly cheaper than 300 Euros.

    Regards,

    JH

  17. #17
    Join Date
    Dec 1969
    Location
    Mountain View, California - Silicon Valley
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    Default

    Hey, Guys, Mezigot, Gingerbeer, Frank, et al.
    I kind of fell off the cart here for a while, hospitalized, out of action for some time. All good now. I just thought to mention something I do which violates the canon, but I've done it for years with good results in my four K31s. My brass is separated by rifle, 100 per, and I fireform and then neck-size, until there is the very slightest resistance to chambering, (I check before reloading a batch) then I bump back the shoulder and all is good again. Brass lasts a long time this way, and I have never, ever had a stuck bolt or hard extraction. In the last year I have been using the Lee Collet die, which squeezes the case around a mandrel and doesn't move the brass around very much. I really like it. Can't go wrong with those competition RCBS dies, I have the bullet seater, and use Redding for neck-sizing, RCBS for full-length resizing, and now the Lee die for neck-sizing. My groups hover around 1.5-2.0" but if I include called flyers (hey, I'm 62 and experiment constantly with orthoptics, but still don't focus very well), then they open up to 3" or worse. I shoot 10 shot groups, 100 yds., and usually get six or seven in a really nice group, but blow a couple of shots. But I'm only competing against myself, so it's always a fun challenge to run a good 10-shot string. I feel that the rifle would shoot consistent groups for a better shooter, but who knows? I shot ISU competitive pistol matches here in the USA (Free, Std, Centerfire & Air Pistol) for a number of years, and have a pretty good sense of calling the shot location when the trigger breaks with the sights out of alignment. That is why I think it is operator error that causes the flyers.
    Also, what I wanted to write in the first place is to Frank, the die set you want, RCBS 38601, I can get for you @ $79.00 plus shipping from Graf & Sons to me, and me to you. If this would be helpful, send me an e-mail (better) or
    PM me (switching browsers, not so good), and we can talk.
    Best regards to all, Kari Prager
    Best regards,
    Kari Prager

    "Schiessen und Treffen, nicht Schiessen und Knallen."
    "Meine Waffe", Oberstlieut. Mariotti, Schweizerische Armee, 1918

  18. #18
    Join Date
    Sep 2009
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    Springfield, or
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    Default

    Ok, not trying to resurrect a old post, but it contains information that I was looking for. If any of these original people are still here, Mezigot, Gingerbeer, GunsGunsGuns, I have a question about loading this cartridge with larger cast bullets. Someone on Swiss rifles forum was saying they was loading with .321 cal bullets. Is this safe? This seems to me to be way off the .005 safety margin for over sizing bullets. I understand the need to fill the need to fill the throat up as much as possible but really how much difference is really made by the .010 difference between a .311 and a .321. I know that the difference between a .308 and the .321 throat probably is why the gp90/23 did not preform well in these rifles. I eagerly await a reply on this.

    Travis

  19. #19
    Join Date
    Dec 1969
    Location
    Connecticut
    Posts
    557

    Default

    One of the guys posting on this subject at that other forum is pretty confused. Having seen some advice that CAST bullets up to .321" diameter may perform well, he has extrapolated that JACKETED .321" bullets would be a good idea. Clearly, he has no concept of the different force required to stuff an oversize jacketed bullet into the bore as compared to that needed for a cast bullet (or a swaged, paper-patched design as used in GP90).

    The GP90 bullet does, indeed, have a major diameter of ~.321"+ - but ~.006" of that is PAPER! The bare lead shank under that paper has a major diameter of about .316" and its rear section is reduced to ~.302". With the paper patch, the heel section goes ~.307". This configuration offers a great deal less resistance to being shoved down a ~.296" X .308"+ barrel than does a tough-jacketed .321" bullet.

    If you want to experiment with oversized cast bullets in a rifle chambered for 7.5x53, prudence dictates a major diameter (bare) of not more than ~.316" and optional paper patch adding up to .006". If the bullet doesn't feature a rebated heel, we can expect some major problems with "fins" at the bullet base possibly causing erratic flight.

    In my own limited experiments with a Schmidt 1889, I found no practical performance difference between gas-check bullets (Lyman 311467) sized .316" or sized .311" - both grouped about 2.5" at 100 yards with issue sights, essentially the same as jacketed 180-grain RN bullets in either .308" or .3105" diameters.

  20. #20
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    Sep 2009
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    Springfield, or
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    I am not trying to extrapolate anything. I think that I have come to the conclusion that .311 cast bullets would be the best choice singe the major diameter of the nonrebated part of the bullet is closet to .311. I will just size my brass up to 311 using a Lyman case neck sizing die. using a .321 just seems like pushing to much and just putting that muck more stress on a 100+ y/o barrel. The 1889 was designed for lead bullets so I think I will stick with lead and stay away from jacketed bullets alltogether.

    Travis

  21. #21
    Join Date
    Dec 1969
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    Benelux
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    All the info is here ready available, use it in the reloading section of the forum...

    http://theswissriflesdotcommessageboard.yuku.com/

    Guisan.

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