Fireforming cases???

Discussion in 'The Ammo & Reloading Forum' started by Guest, Feb 24, 2003.

  1. Guest

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    polishshooter
    Senior Chief Moderator Staff
    Posts: 1617
    (9/19/01 10:01:30 pm)
    Reply | Edit | Del All Fireforming cases???
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    Problem: 8x56RH cases are formed from 7.62x54R cases...they are dimensionally identical, except for the silly 2mm length and the angle of the shoulder...the Russian is sharply angled, the Hungarian is like a coke bottle, rounded. And of course, the mouth is wider, .329 vs. .307-.311. The Russian cycles and chambers as is in the M95.

    Now, RCBS makes a "case forming die," but it is believed to be just something that fits on the $80 custom RCBS sizing die, won't work with the new cheap Lee dies probably...

    SOooo... Why couldn't a guy take once fired Russian, fired through a Mosin of course, neck size only, load a medium load behind a .329 bullet, and fireform the case?????

    Never done anything like it, so what do you think, rifle guys? Would it work?

    Or am I gonna blow up my pretty Steyr...
    Well, I didn't win the Powerball, so I still collect Russian Crap and variants thereof. ( And am darn happy I can!)

    kdubaz
    Moderator
    Posts: 660
    (9/19/01 11:07:22 pm)
    Reply | Edit | Del Re: Fireforming cases???
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    Polish -

    Case forming dies are just that - separate dies. They don't fit onto other dies. In some cases (no pun) there may be a set of 2 or several staging dies to complete a forming die set.

    The tolerances you give don't sound major, and you may well be able to fireform for your needs. Have you tried chambering a dummy round after necksizing up to the larger diameter? Guess you have, it you state it will chamber and cycle through insertion/extraction. Going from a gently sloped shoulder to a sharper one usually doesn't present too much of a problem - I've never tried going from a sharp one to a more gentle one.

    The one thing you have to keep in mind is the relative strength of the two actions. Isn't the Styer a one-lug bolt? Sorta like the ol' Krag - not too strong. If the cartridges, in their original form develop the same basic chamber pressure, and if the two actions are of similar strength, then fireforming using reduced loads of fast powder (5-6 gr. of pistol type powder, Unique, bullseye, etc) with a filler to hold it back against the primer and a wax or grease plug in lieu of a bullet should fireform the cases for you. Normally, I use a nearly case full of real slow burning powder to fireform with, but I'm dealing with good, strong actions. I would certainly start my rifle loads at the very bottom of the loading charts and slowly work up a grain at a time, watching for pressure signs all along the way. Watch also, for case stretching signs if the case has a lot of length to compensate for. If you get case separation - the length is too much to overcome.
    Keep below the ridgeline!

    Edited by: kdubaz at: 9/20/01 12:11:38 am

    polishshooter
    Senior Chief Moderator Staff
    Posts: 1623
    (9/19/01 11:29:28 pm)
    Reply | Edit | Del Re: Fireforming cases???
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    No, it's two lug, but I was told the action is rated for only like 45,000 if I remember, a conversion to the Russian was not recommended by a custom barrel maker I contacted, too much pressure, he recommended .30-40 Krag...

    But then I've had others tell me the 95 was the strongest straight-pull action ever, and the 7.5 Schmidt Rubin is a pretty hot round I think...and the Schmidt was never considered weak.

    I still think people are prejudiced because they think intuitively a turn-bolt would be stronger, especially if there's a third locking lug, but what is a Semi-auto like a Garand but a similar 2 lug action? And nobody thinks IT'S weak!

    That shorter case should help too, don't you think?

    Stupid question...can only rimmed cases be fireformed? How would you control headspace otherwise?


    Well, I didn't win the Powerball, so I still collect Russian Crap and variants thereof. ( And am darn happy I can!)

    Edited by: polishshooter at: 9/20/01 12:32:20 am

    kdubaz
    Moderator
    Posts: 664
    (9/22/01 2:26:52 pm)
    Reply | Edit | Del Re: Fireforming cases???
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    Any centerfire cartridge case may be fireformed - doesn't have to be only rimmed. All my present wildcat calibers are rimless cases.

    The shorter case could be both a help and a hinderence. Too long, and you have a lot of forming and trimming to do with forming dies. Too short, and the case may stretch excessively in the forming chamber and cause weak walls, or even separation.

    Don't both cartridges generate basically the same pressure, i.e, 45K psi? If so, the actions should be of similar strength and the converted rounds should be safe to load and shoot. Just remember, slower burning powders will shoot cooler, spread the pressure peak over longer duration and usually, provide the best type of propellent for the older cartridges. I would look at loadings starting with IMR 4530 and on down the burn rate tables to find a powder that will provide the least pressure for the fullest case loading and still provide a degree of velocity/accuracy desired.
    Keep below the ridgeline!
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