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What could be causing my OAL differences?

Discussion in 'Reloading' started by XDRoX, Apr 21, 2010.

  1. XDRoX


    Jan 24, 2009
    San Diego
    I just loaded some rounds on my 550B.
    Shortest round = 1.136"
    Longest round = 1.144"
    That's quite a difference. I don't remember having this problem when loading on my SS. I think I'm pulling the lever the same every time, but it's hard to say. Could anything else be causing this issue?
    The vast majority of my rounds are right at 1.142" (or very close) which is where I want them. These are the extreme outliers and are rare, but still occur now and then.
  2. DrunkenParrot

    DrunkenParrot THE RESISTANCE

    What manufacture are the bullets from? I have bought cheap bullets that were quite different (Remington, Rainer) this could be your problem

  3. XDRoX


    Jan 24, 2009
    San Diego
    Thery're Rainier, and yes they were cheap. They weigh different and measure slightly different. I considered this could be the problem, but does it really matter how long the bullet is? Shouldn't the seating die just be measuring total round length? If a bullet is longer then wouldn't it just get set deeper?
  4. RLDS45S


    Jun 8, 2003
    It comes w/territory....go measure some SMK's they vary in oal. R U using the right seating stem? No worries with variances.
    Last edited: Apr 21, 2010
  5. tlafrance

    tlafrance Missing AZ

    Feb 5, 2001
    On a 550:

    Loose shell plate (tighten center pivot screw and lock screw)


    You set your OAL with no shells in the other 3 stations. ALL stations should be full when setting adjustments.

  6. wanderinwalker

    wanderinwalker 6 of .44

    Feb 13, 2003
    New Hampshire

    It's true. I wouldn't worry about that much variation in pistol rounds. More than likely the bullets. Rifle match bullets will drive you batty if you use the tip of the seated bullets rather than a comparator. I actually end up seating my .223 match ammo a bit on the deep side (AR mags will take an OAL of 2.26", but I normally look for 2.25-2.255" just to be safe) because of these variations.

    Load, shoot, repeat, be happy! :whistling:
  7. n2extrm


    Feb 24, 2009
    The ogive or the nose of the bullet may be slightly different on one to the next. What press are you using? Sometimes on a 550 if you set it up with only 1 case then run it with all four on the ram the die setup will change a little. Colorado had some tips I think in his sticky on how to take up some of the tool head slop. I don't think you can really get them all identical unless you measure them on the ogive and all brass is the same, all slop is removed and the bullets are real high end. Even then they would most likely vary a little.
  8. fredj338


    Dec 22, 2004
    Yep shell plate &/or tool head slop will give small variations in OAL. So will the cheaper bullets as nose shapes vary a little from bullet to bullet. Tighten the shell palte so it just turns. Shim the tool head snug or take it out, turn it over & dimple each side of the tool head key so it snugs up in the press. Even w/o, that small diff will not really affect your loads accuracy or pressures.
    Last edited: Apr 22, 2010
  9. XDRoX


    Jan 24, 2009
    San Diego
    Thanks Fred. If the difference won't really effect accuracy or pressures, then I am fine with it.
    BTW, Dillon's new seating dies comes with a reversible seating stem. That's why I couldn't find it in the box the other day. You just take it out and flip it around to seat HP's or FP's.
  10. Patrick Graham

    Patrick Graham Footlong Jr.

    Sep 7, 2001
    Kokomo Indiana
    That's a variation of .008" isn't real good but it's not real bad either for cheap bullets.

    I bought some factory seconds 115gr 9mm from berry's a while back. They run about .010" in overall length variation when loaded. That's awful, and that's after culling the absolute just bullets out.
    Last edited: Apr 22, 2010
  11. fredj338


    Dec 22, 2004
    There ya go. Yep, a 0.008: diff is probably the bullet mor ethan anything else, but means nothing. When you start getting bullets deeper than 0.050", then you start top see pressures go up a little.
  12. Colorado4Wheel


    Nov 2, 2006
    Edit, found it.

    Check your seating die for burrs inside the stem. I'm sure your using the concave one not the flat one right?
    Last edited: Apr 22, 2010