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Thread: Flat primers

  1. #1

    Flat primers

    I'm loading for a .30-06
    using Hodgdon H4350 165gr bullets, trimmed cases, Win primers

    Looking at the Hodgdon website it states:
    Starting load at 53.0, max load 59.0

    Looking at a American reloading forum the best recipe was 57.5 and a number of people agreed with that finding.

    I loaded this recipe and found I was flatning the primer. I tried 56grns of powder and it did the same but to a lesser extent. Tomorrow I'm going to start at the lowest and work my way up.

    Why is this happening when I've followed all the guidelines. Have I got to much tension around the neck of the round? Using the kinetic hammer doesn't show any real marks of over tightning.

    Your thoughts please.


  2. #2

    Even if you were applying a heavy crimp l fail to see how neck tension alone could cause pressure to that extent.
    What's you AOL, could you be jamming the lands too much??
    Are you using a chrono' to log you velocity?

  3. #3
    There are a few reasons this could happen. The first thing is that you didn't follow all the guide lines. The first and foremost is that you always start at the bottom and work up. Always. The reason for this is because every rifle and every set of seemingly identical components are different and will act differntly when combined. I remember well a 17 caliber that blew primers out with starting loads! If I'd decided to go with the "popular" load of the time I'd have blown the action up and my face with it. Another person's loading data, or a group of people giving you a thumbs up on a load is no reason to NOT start at the bottom.

    To your problem: Are your cases full Length resized or new? Cases that are undersized for the chamber can flatten primers as the primer will come out before ignition/pressure slaps the case rearward in an oversized chamber (or if it's an undersized case) which flattens the primer. With new brass this can be avoided in a couple of methods, the simplist of which is to seat the bullet out to, and lightly into, the lands on the first firing. This will support the case against the bolt face and you will have a cartridge fit to your chamber. From there you can partial-resize to maintain the fit for several firings.

    You don't mention that your cases are trimmed. Impingment of the case mouth in the leade will cause excessive pressures. Crimps will rarely do so unless you were over-loaded to begin with.

    Stick to basics and load safely. Reloading is not a referendum proposition: It's you and your rifle: No one can give you a safe load for it. Good Shooting.~Muir

  4. #4
    Yes the cases are full length resized. Case's were trimmed OAL is 3.276 which is 20 thou off the lands.

    Point taken about starting at the bottom and working up. i did that very thing when I worked on a load for my .243 and even for other .30-06 loads.

    As yet I dont have a chronograph.

  5. #5

    Primers can also make a large (scarily large!) difference to pressures.

    Are you by any chance the Oxfordshire based Elma Fud? If so I have a Chrono you can borrow.

  6. #6
    What is the chrono saying?


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