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Caliber Conversion Help

This is a discussion on Caliber Conversion Help within the Up To .375 forums, part of the HUNTING EQUIPMENT, FIREARMS & AMMUNITION category; I need a fifties era chamber conversion solution and wonder if anyone still does it. Picked up an '03 Mannlicher ...

  1. #1
    Red Leg's Avatar
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    Default Caliber Conversion Help

    I need a fifties era chamber conversion solution and wonder if anyone still does it. Picked up an '03 Mannlicher Schoenauer (originally 6.5 x 54) at a gun show that had been converted to 6.5x57. Got it home and the usual slick action won't handle the 6.5x57's at all - three rounds jam it up and two feed like an industrial project. 6.5x54's on the other hand feed like butter, so who ever rechambered the rifle didn't screw up the action.

    Rebarrelling would be complicated because the full length stock would demand the exact barrel contours, and a Schoenauer also has unique sight shaping. Soooo does anyone today reline chambers to create a smaller caliber? In this case - a very slightly smaller one. Going to anything other than 6.5x54 is not feasible because of the tight dimensions of that rotary magazine (witness the 6.5x57s). Any ideas?

    I am half way tempted to fire off a 6.5x54 and see how dramatic the "fireforming" result will be. To date, the thought of digging out a jammed split case has kept me from doing that.
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    DO NOT FIRE 6.5X54 AMMO IN A 6.5X57 CHAMBER! You won't be simply dragging out a split case, the case head will likely separate and spew hot pressurized gasses back into your face and arms at a bare minimum, or the rifle will simply come apart and send shrapnel everywhere. Not only is the headspace wildly excessive but they are two different head diameters, the 54mm round being the narrower, so you cannot even handload rounds with the bullet jammed into the lands (the normal fireforming method) to solve the headspace problem.

    Lining the chamber has been reported to work with some low-pressure rounds, but will not be useful at these pressures. Besides, it will likely cost you as much or more than a rebarrel job, which by the way, would be the only satisfactory method. Many barrel manufacturers are be happy to taper a new one identical to the existing one for a modest added charge.

    The other consideration is whether the bolt face has been altered. If it or the extractor altered, that will also need to be addressed in order to function correctly with the smaller cartridge.

    I do not know what you mean by "jamming up" but it will be far more expedient and cost effective to have a gunsmith EXPERIENCED WITH THAT PARTICULAR RIFLE alter the loading ramp, feed rails or whatever to feed the larger round. I might also suggest a call to the Collectors Assn to get their input and perhaps a gunsmith referral to send it to for suitability evaluation before tackling any alterations.
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    Red Leg's Avatar
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    Quote Originally Posted by Stocky View Post
    DO NOT FIRE 6.5X54 AMMO IN A 6.5X57 CHAMBER! You won't be simply dragging out a split case, the case head will likely separate and spew hot pressurized gasses back into your face and arms at a bare minimum, or the rifle will simply come apart and send shrapnel everywhere. Not only is the headspace wildly excessive but they are two different head diameters, the 54mm round being the narrower, so you cannot even handload rounds with the bullet jammed into the lands (the normal fireforming method) to solve the headspace problem.

    Lining the chamber has been reported to work with some low-pressure rounds, but will not be useful at these pressures. Besides, it will likely cost you as much or more than a rebarrel job, which by the way, would be the only satisfactory method. Many barrel manufacturers are be happy to taper a new one identical to the existing one for a modest added charge.

    The other consideration is whether the bolt face has been altered. If it or the extractor altered, that will also need to be addressed in order to function correctly with the smaller cartridge.

    I do not know what you mean by "jamming up" but it will be far more expedient and cost effective to have a gunsmith EXPERIENCED WITH THAT PARTICULAR RIFLE alter the loading ramp, feed rails or whatever to feed the larger round. I might also suggest a call to the Collectors Assn to get their input and perhaps a gunsmith referral to send it to for suitability evaluation before tackling any alterations.
    All good points Stocky. That was somewhat tongue in cheek; I am confident the 54 wouldn't headspace in any case. Communicated with Ross Seyfried on it and am awaiting some other input. The original barrels have integral sights with fairly demanding contours and I not sure who could duplicate that.

    Both Ross and JJ Perodeau believe that the rotary magazine cannot be altered effectively - they were designed for very specific cartridge demensions- which explains why the 57s jam the rotor and the 54's do not. The bolt face seems to have no issues picking up and ejecting the 54's. Re-lining chambers and re-reaming to smaller, relatively high pressure calibers is not that uncommon in Europe - particularly with combination guns.

    Frustrating to know after all these years that I can still be caught "investing" in a firearms education.
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    Another thing I've had some luck at on restorations, keep checking Numrich Arms site for a barrel when you think about it. Things like that often pop-up there but don't last for long.

    Ya, I resemble that education remark myself. Hate it when that happens.
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    A new barrel for a M 1903 is hard to get. There was E. Schoder in Austria, who was able to produce barrels for the pre-WWII - Mannlicher Schoenauers. But his shop is allready closed. I know a M 1908 ( 8x56MS) with a new Barrel in 6,5x57, also done in the 50s. No Problems. Try to reload your 6,5x57 with round-nose bullets like the Hornady 160gr. Maybe this is a solution. I have Problems with spitzer bullets in both of my M 1903 ( 6,5x54MS), rifle and carbine. But using long round nose bullets from RWS, Hornady or Lapua - perfect !

    Mannlicher

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    it'snot a "reline chamber" you're looking for (whatever that is) properly the barrel is taken off and reduced by 1 or 2 threads, then the new chamber is cut in, the barrel is set back to allow the new chamber to be cut. On a mannlicher stock, that set the whole front mount back slightly, LOTS of work, not a simple job. I think, if it were mine, I'd get a local smith with a 6.5X57 reamer (GOOD LUCK!!) to try to re-cut to what you suspect is the correct chamber or better yet, slug the barrel and see exactly what the chamber is and what it was cut to.
    If the head diameters are different (without me lookng it up) that explains your feeding issues.

    BTW, I'd fire off a couple of round but wouldn't post it on the internet!!! Not the saf eor right thing to do, but I would.... Safety SUCKS, Press your luck.

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