OK to shoot short brass?

Discussion in 'Reloading' started by arrow, Oct 29, 2012.

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  1. arrow

    arrow Well-Known Member

    Dec 13, 2007
    I got rid of my .308 winchester and built a .243 winchester. I had a bunch of .308 brass laying around so figured I would make some .243 out of it. I ran them through the .243 die and out comes .243 winchester brass. I loaded them up to fireform and everything was fine except for the accuracy. I trimmed them all down so they would be the same length and square. The only problem is they are getting trimmed .020" shorter than I normally trim normal .243 winchester brass. Is this alright to shoot through my rifle? If not, I have already fired 30 rounds like this through, did I do any damage to my chamber? I have heard of people with the same problem turning 7 rm brass into .257 wby brass. Thanks
  2. Kevin Thomas

    Kevin Thomas Well-Known Member

    Feb 16, 2009

    No problem at all, and the .020" short won't hurt a thing. The thing to be aware of when you're reforming cases is neck thickness, not length. This is especially true when necking down, as you're doing here. Check the neck wall thickness with a tubing mic, and the diameter of the neck of a loaded round to ensure that they aren't too far off from a standard (factory) 243 Win case. You might also want to consdier a chamber cast, just so you'll know exactly what the neck dimension is in your chamber. You'll want at least .002" clearance (.001" per side) to avoid any nasty surprises here.
  3. 4xforfun

    4xforfun Well-Known Member

    Oct 1, 2007
    I know a guy who won the 2011 IBS 1000 yard nationals in West Virginia, and used brass that he accedentaly trimmed WAY SHORT. Won the two gun overall, Light gun group (with the short brass), and light gun overall.

    In other words...not a problem.

    Good luck.
  4. green 788

    green 788 Well-Known Member

    Feb 5, 2005
    Heck... he's probably trimming all his brass that short now. :)
  5. g0rd0

    g0rd0 Well-Known Member

    Mar 9, 2012
    no problem, when I was liveing in Alberta I had a 308 and my wife bought a 243, so we down sised some 308 and loaded them numerous times.
    You may want to anneal them as the extreme siseing may have hardened them on the neck and shoulders