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Thread: Gehmann-Konstanz 5.6 x 61 vom Hofe

  1. #21
    collath
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    Sharps, thanks for the tip on how to do that.

    Mike, I don't think the 12.7 is very popular but send me a mail and I will give you my phone #. Sharps you can do that too if you want to talk reloading. Just don't glaze over on me!

    I am going to post the last bit on the vH and hopefully this thread will continue a bit

  2. #22
    collath
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    I hope everyone doesn't mind but I want to post some final thoughts on the 5.6 vH and opinions on loading in general.

    As an alternative to an expensive press (I don’t believe Rich is making the press anymore but his brother may) you could make a set of “bump up” dies or a push through die for your reloading press. Then either squeeze them down or up to the right size. There are tons of .224 and .243 bullets out there that would fit. I use what I call “orphan” loading dies that you buy out of a box at the gun show for two bucks or so or buy some 7/8-16 threaded rod and go with that. It’s easier because you don’t need to full anneal it like the dies before you can cut it.

    However, there are problems with this too. Bumping up has a lot to do with how well centered you can hold the bullet during the process and how evenly the jacket was made. You can get bullets that are slightly out of balance because the jacket didn't stretch evenly or they weren't perfectly centered. But I have found that by only bumping a few thousandths like you do for the vH accuracy is more than adequate and the jackets stay tight. On the other hand swaging them down will also work if done incrementally. But the jackets sometime seem to get very slightly loose from the core. I think this is due to the jackets springing back. Bonded cores fix this issue and these are accurate as well. My preference is to bump up jacketed bullets and swage down lead bullets. I will be testing some 80 grain 224 A-Max bumped up soon. Here are some pictures of bullets and cases:

    vH Cartridges.jpg

    Starting from the far left is a 77 grain BTHP I made.

    Next is an 80 grain BTHP I also made. Note that I made the jacket somewhat longer and left a deep hollowpoint in this bullet. I don’t see any real difference between the 77 and this 80 as far as performance goes. I expected that it may have a better BE but I haven’t had a chance to shoot it at long range to tell. The longer bearing surface and slightly higher weight doesn’t seem to be making much difference in pressure

    The next one is a Hornady 80 grain .224” V-max that I bumped up to .228”. I was working on loads for this when the cold weather hit.

    The first case to the left is a Remington 25-06 resized to vH. If you look closely you can see a small buckle in the shoulder. I believe this is caused by too much of an anneal in that area. The shoulder was just a little too soft and most likely I got sloppy with taking too much sizing. Usually I take only about 1/16th of a turn down after the die hits the shoulder until I get it pushed into place.

    The next case is a Nickel Plated Remington 25-06 and here you can see the slight bulge around the base of the shoulder. For me there just seems to be no way around this happening. Also if you look very carefully you can see some small lube dents at the transition from the shoulder to the neck. Lube gets trapped in this area.The bullet in the case is a resized A-max. The shoulder dents blow out during forming but the tiny lube dents seem to stay.

    For comparison, the last case is a Horneber loaded with a 70 grain .227” Hornady Savage Hi-power bullet

    Also I confess that I don’t care about efficiency I only care about what works (for me) and if powder blows out the end of the barrel its OK with me. I’ll buy more. The main problem I see is these powders burn fairly dirty because of all the deterrents and I have accuracy issues due to fouling. H-870 was really bad for this. I could get three shots almost touching and the fourth would go off more than a little and the fifth would hardly hit the paper. This was during very slow fire with a lot of cooling between shots. Running a solvent patch through the bore and then a dry patch was all that was needed to bring it back. The newer powders are a little better in this respect. Lastly, burning a hatful of slow powder at relatively high pressures does nothing for barrel life, so to protect this barrel, I generally load to a much lower velocity. I only stepped it up to see if I could make the early claimed velocities. I do believe they are within reach with today’s powders.

    I do all my testing using a friend’s RSI Pressure Trace system coupled with my Ohler 35P chronograph. I measure the barrel thickness at the chamber using a NDT 715 ultrasonic thickness tester with a small transducer. This device can measure down to one thousandth of an inch and I use that to calibrate the strain gauge. I have recorded average velocity with my bullets at just above 3,600 FPS at pressures of just over 57,000 psi. I think there is a bit more left to get but I have quit that for now to spare the barrel. Unusual guns and calibers are my passion and reloading just makes it better. I know I have gone on more than long enough. Thanks everyone for reading this longwinded report. Please all comments are welcome.

  3. #23
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    Excellent! Enjoyed every word. One could certainly call that a 'slope shouldered' case, to borrow a phrase from Elmer Keith and Skeeter Skelton.

    The 'boat tail' on the bullets is interesting, more of a rebate than a boat tail. Having never swaged bullets is that because they're 'home swaged' and that type of boat tail is necessary because of the tooling when done at home? Or could a conventional type boat tail be swaged? No matter, just curious.

    Dents from case forming or wrinkles from annealing. Waddaya do? They happen. Once fireformed all is usually well, at least in my experience. I'm more than a bit fond of unusual, obsolete and obscure cartridges. With the exception of the 9 X 71 Peterlongo most of the ones I've fooled with are considerably older....but I'm weird, I LIKE black powder....hehe.

  4. #24
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    Quote Originally Posted by collath View Post
    Do you happen to know what the maximum pressure was supposed to be. I have a listing that shows the MAP pressure at 4400 bar and that is a lot!
    The CIP max MAP according to the DEVA handbook for the rimless case is 4550 bar, piezo-electric transducer, but for the 5.6x61R (rimmed) it's only 3800 bar.
    The DEVA handbook also Shows that 77 gr Gehmann, 61 gr H 870 load at 3617 bar, just within the limits for the R case. Another 77gr bullet load is given as "max pressure for the rimless case: 53.2 gr IMR 4831 for 3510 fps. But a warning: The 5.6x61R is long out of print, since DWM stopped making ammo in the early 1970s. The fatal blow to the rimless version popularity came when some Mauser 66 rifles supplied by W.Gehmann (66 invented by him too) blew up with Gehmann supplied "factory" loads. A case of secondary explosion due to slow powder and too much airspace? The cartridges coffin was nailed shut when a change in the German hunting laws prescribed a minimum bullet diameter of 6.5 mm/.25" for all hoofed game other than roe deer, making it illegal for use on the increasing numbers of wild boar here.

  5. #25
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    This has been a great discussion so far. Please continue. The only thing that would make it better for me is if I were there watching you swage.
    Peter

  6. #26
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    Collath,
    I also believe that some small dents are caused by the brass folding in on itself in the forming,in my case this is where a small crack forms ,either in fireforming or the first loaded cartridge.Thats a lot of work to lose the case so soon. I'm really interested in your measuring the pressures, the ability to do this would take a lot of guesswork out of loading calibers that don't have much published data.I make .318 bullets by sizing .321 32Win Spec bullets, and Gene made them by bumping up 308 bullets.I believe its much better to size them down,as long as you don't go over .005"(note .323" would work); and it is certainly easier. I found a box of Nosler 80 gr HPBT competition bullets.I will PM you with my phone number and Email address.
    Sharps4590,
    I believe they use a rebated boatail because the dies don't have to have a knife edge on at the junction of the boatail and shank of the bullet.A knife edge would soon break due to the pressure required in forming.
    Axel,
    I suspect the introduction of the 5.6x57/5.6x57R also helped in the demise of the vH. It is much simpler than the vH,and useful for the same animals.I believe the are both still legal for Gams in Austria and in other countries legal for other game. If I ever get my project finished, I will be playing with a 5.6x57,rimless version.I have a good bit of ammo,so I won't have to load hunting ammo,just target,etc.
    Mike
    Last edited by mike ford; 02-25-2015 at 01:00 PM.

  7. #27
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    Quote Originally Posted by mike ford View Post
    I suspect the introduction of the 5.6x57/5.6x57R also helped in the demise of the vH. It is much simpler than the vH,and useful for the same animals.I believe the are both still legal for Gams in Austria and in other countries legal for other game.
    Mike, of course the 5.6x57 was a direct competitor to the 5.6x61, but it's one of the worst designs for handloaders IMHO. As an advantage, it uses now standard .223" - .224" bullets. But the designer made a blunder: From the start they intended the cartridge to be "ideal" for the use of adapters that would allow to use other .22 cartridges from .22lr to .222 Remington in the rifles. So they designed the case with a very thick case neck. This thick neck is a big problem in handloading. It has to be expanded and annealed to EXACTLY the right size for holding the bullet. If a wee bit to large it will not hold the bullet, if a wee bit to small it will "resize" most bullets, so any accuracy goes down the drain. Bullets may even been mutilated if factory ammo is stored for some time. Most people who bought such a rifle when the 5.6x57 was introduced with much ballyhoo as a long range roebuck rifle now got rid of them, if they found some fool. I would rather go to any other exotic cartridge like a .475 #2 Jeffery than spending time, tools, powder and so on with such a useless design.
    Last edited by Axel E; 02-24-2015 at 10:01 PM.

  8. #28
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    IIRC such a "rebated boat tail" bullet was also featured on the super accurate Finnish 7.62x54R load.

  9. #29
    collath
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    Axel,

    That is a huge amount of pressure. Is the MAP calculation done at 14.5 or 14.7 psi per bar as that makes a difference with these numbers? By my calculation 4550 bar @ 14.5 is 65,992 psi while at 14.7 it is 66,885 psi. These are very high numbers in my mind. I know the Mauser is strong but is it really THAT strong? I think the case will start to flow at those pressures.

    Just for fun I ran two hypothetical loads through my computer using a maximum pressure of 66,000 psi with my 77 grain bullet and 26 inch barrel. I ran an H-870 load since that was supposed to be the powder they used and it needed a 109.6% loading density or almost 6 grains over a full case to give 65,806 psi and a projected velocity of 3711 FPS. I will not mention the powder in the second load but it came in at a calculated 65,811 psi and 3746 FPS. This load was 103.5% loading density which I think you could actually do with this powder. That puts the velocity in the range of what they were advertising. Just for fun I added 4 inches to the barrel length and got 3863 FPS and 3902 FPS respectively with everything else being the same.

    Lastly I thought I would plug in that last load with 53.2 grains of IMR 4831, 30 inch barrel and my 77 grain bullet since all the specifications are in already. Also all these and those above calculations are based on the Horneber case capacities. The result is a CALCULATED loading density of 95.1% but a pressure of 69,882 psi at 3742 FPS. At 95% I doubt if the infamous secondary explosive effect would come into play but I tried 53.3 grains or +0.1 grains and got 70,272 psi and with 53.5 grains calculated pressure was 71,058 psi. Very small additions of this powder yield fairly large increases in psi.

    Please keep in mind these are calculated pressures and velocities not actual measured numbers but it does show where it could go.

    I think there were several match quality cartridges coming out of Europe with rebated bullets. They seem to work for me.

    Axel, all I can say is you must have a huge library of reference books coupled with a lifetime of experience and that I really appreciate your input. Thank you very much!

  10. #30
    collath
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    Peter,

    Thank you for the kind words and if you live close you are welcome to visit anytime. However, I assure you swaging bullets is boring as mud. Shooting them is something else again. Thanks.

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