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Head space gauge

Discussion in 'Reloading' started by motorcyclist, May 21, 2014.

  1. I've started loading 308 for a M1a and many recommended using a head space gauge. I bought a L.E. Wilson and cleaned some once fired brass, a mix of Federal, R-P and Hornady. I started adjusting the die down and ran out of adjustment with every case still just proud of the top of the Wilson gauge. I tried some unfired factory ammo and it drops in perfect. The dies are Lyman AA. Old (1970's) but looked unused when I got them in some trading. I would think 308 then is 308 now. What am I missing?
  2. steve4102


    Jan 2, 2009
    What do you mean by, "Ran out of adjustments"?

    Many FL dies recommend to screw the die into the press until it touches the shell holder, Plus 1/4 turn more. Lee dies say up to a full 1/2 turn more. Are you past the 1/4 + Turn more?

    These gauges can be misleading. Often times the case will not enter the gauge fully because the rim or the web is slightly distorted from the action of the semi-auto. The sizing die does not contact these points so they simply don't fit.

    Many erroneously assume this is a headspace issue and keep screwing the die into the press further and further with no relief.

    Then the comments and suggestions will come flying to get a small base die, that will fix it, nope.

    Simple test to see if your case rim or web is distorted. Stick it into the case gauge headstamp first. If it doesn't enter the gauge you know that it isa rim/web issue and not a headspace issue.

    You can also check your sized empty cases and see if they chamber and extract with ease in YOUR rifle. If they do, put the gauge into the drawer where it will stay safe and not bother you any more.

  3. steve4102


    Jan 2, 2009
    Last edited: May 21, 2014
  4. fredj338


    Dec 22, 2004
    steve gave exc advice. I had to snug my RCBS dies 1/3 turn after contact with the shell plate on my 550 to get the shoulder pushed back on mixed brass. My handloads feed fine in 4 diff ARs. As noted, your rifle's chamber is the final word, but for me, it was just easier to use the gauge.
    Last edited: May 21, 2014
  5. Thank you both! The lyman instructions say till it touches the shell plate. I just added a 1/2 turn and tried a few cases. They drop in to the gauge perfectly. I was thinking "running out of adjustment" as I was out of thread on the die body for the lock ring when touching the shell plate. Now I have lock ring thread showing above the die body but that won't harm anything. I'm learning. I'm off to fine tune as that 1/2 turn is probably more than I need. Thanks again!
  6. steve4102


    Jan 2, 2009
    If I understand this correctly, yes it will harm something.

    The lock ring should be used to secure the die to the press. There should be no " lock ring thread showing above the die body".

    The lock ring should be loosened and moved all the way to the top of the die.

    The die should be adjusted for proper sizing.

    Once that proper sizing position is achieved, the lock ring should be screwed all the way down to the press and "Locked". This will keep the die in the same position while in use and again when you re-install the die into the press.
  7. PCJim

    PCJim Senior Member

    Aug 4, 2008
    I'm going to add to what Steve stated. You should strive to have all the threads of the lock ring engaged with the die's threads. On some presses, you can secure the die to the press by using the lock ring beneath the press body, on the ram side.
    Sometimes, we need to just think a bit outside the box...
  8. F106 Fan

    F106 Fan

    Oct 19, 2011
    Mounting the lockring to the underside of the toolhead works but it loses the constant adjustment of a ring clamped to the die.

    OTOH, who cares? It's not like adjusting the sizing die is magical. Turn it down until it touches the shell holder, turn it down some more and secure the die.

    Personally, I wouldn't worry too much about having lockring threads showing above the die. All the lockring has to do is keep the die in adjustment for the duration of the batch. It will be pretty easy to know if the die has backed out. The 'cam over' won't feel right.

    If I was concerned, I would consider extending the shell holder which will move the die up in the toolhead:

    MidwayUSA also has caliber specific extended shellholders.

  9. BobbyS

    BobbyS Truth always sounds like lies to a sinner

    Feb 14, 2010
    Boonies New Mexico
    I have never seen that gauge before. Very interesting idea, to be able to see what is going on. Thanks!
  10. Steve, with the die adjusted (it wound up between 1/4 and 1/2 turn past touching the die plate) I screw the lock ring down to secure the die and tighten (snug really). I have about 1/2 the lock ring threads above the top of the die body threads. It's a Lyman die and I'm using a Redding T-7 press. The die appears to just not be long enough.