good fireforming load for 7mm r.m.

Discussion in 'The Ammo & Reloading Forum' started by myfriendis410, Jun 15, 2012.

  1. myfriendis410

    myfriendis410 New Member

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    Anybody have a good fireforming load for the 7mm rem mag? I have a Ruger #1 with an out-of-spec chamber that I would like to customize brass for. Never having done this I am soliciting suggestions. I'm thinking Unique with some Sierra 160 gr. Gamekings hanging around the bench.
  2. Alpo

    Alpo Well-Known Member

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    I know a feller that fireforms 9.3x57 brass out of 8x57. 14 grains of bullseye and a small wad of toilet paper. Puts it in the gun, points it in the air, and pow.

    Ain't no sense to be wasting real bullets.

    Or, if it's just a little off, you could try this.

    I ran a 30 caliber plug down some 7x57 brass, and then backed the die all the way out, and sized the neck down a little at a time, checking after each reduction. Eventually I had a case that the neck was skinny enough that the cartridge would go far enough forward for the bolt to close. The shoulder was not back where it belonged, though. I had, in essence, made a false shoulder for the rifle to headspace on.

    [​IMG]

    Load it as normal and fire.
  3. howlnmad

    howlnmad Well-Known Member

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    Alpos suggestion will work but I like to put a little toilet tissue on top of the powder and then fill the case with corn meal. I think the meal helps the case blow out better and fill the chamber. And it smells like someone is baking cornbread :D.
  4. Bindernut

    Bindernut Well-Known Member

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    Like Alpo, I'll second the neck-up/neck-down procedure to put a "false shoulder" on the brass so it headspaces enough to fireform to the chamber.
    This is how I've done several surplus rifles that had excessive headspace.

    If you're doing a full fireform, I wouldn't bother with bullets either.
    Instead of the tuft of TP, a local fellow here uses wax bullets. He jams the case neck into a thin block of paraffin wax about the length of the bullet neck.
    I'm not sure what powder/charge he uses though.
    Having made my own wax bullets for .22lr I'm sure it's a mess to clean up but it will work.


    How sloppy is the chamber in this particular rifle?
  5. soundguy

    soundguy Well-Known Member

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    and why sloppy?

    I just got some free 30-30 brass.. much of it was so out of spec from being in a sloppy chamber I couldn't even chamber empties in my savage bolt gun.. had to resize and trip just to get them in mostly. forced a few in my marlin lever action 336 to deactivate soem primers though..
  6. howlnmad

    howlnmad Well-Known Member

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    The false shoulder is a good idea when fire forming from one caliber to another. In this case, myfriends410 is only forming 7 mag brass to fit his 7 mag chamber so it shouldn't be needed.
  7. myfriendis410

    myfriendis410 New Member

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    I tried the above suggestion; necked up to .30 caliber and then necked down to 7mm just far enough to allow the brass to chamber, barely. I also tried fireforming, but when I put the brass through the die at the same setting as above (7mm) it returned it to the shorter o.a.l. I went ahead and loaded three rounds using the first technique and will try them out on Monday.
  8. soundguy

    soundguy Well-Known Member

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    post results!
  9. myfriendis410

    myfriendis410 New Member

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    So I got out to the range today with two loads: a mid-range 140 gr. Sierra and a hotter 150 gr. TSX. Both loads were created after a false shoulder was sized into the cases. No signs of case failure and the brass fell out of the gun. I put a tool into the cases and no sign of a ring in the cases. What was interesting is these fired cases only expanded .003" as opposed to the original brass which lengthened .018".

    Thanks for all of the advice. I'm looking good now.
  10. JLA

    JLA Well-Known Member

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    Belted cases are notorious for loose headspace. Best way to tighten it is to necksize the fired brass so itll headspace on the shoulder and the belt.
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