question about OAL

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  • question about OAL

    Hi Gents,

    I'm due to receive a new stock for my rifle and as it comes with a slightly longer magazine I can now seat the berger hybrids to the lands.

    As a result, I've started to get a little more precise with my OAL's - using a hornady OAL gauge, I pushed the bullet until it contacts the lands, then backed it off 0.001 for my final seating. I'm using a comparator gauge to measure to the ogive. the issue is when I use a texta to mark the bullet and chamber it, I can still clearly see where the lands are contacting the bullet?

    I assume that if i can see the lands on the bullet, then the bullet is actually jammed and not seated off the lands is this correct?

    if not can anyone help me out with where I'm going wrong?

    any help much appreciated!

  • #2
    Setting your Hornady OAL Gauge with Bullet. Don't push too hard or you will jam the bullet very easily as they have a long slender taper. It takes very little to none at all to find the lands. If you jammed it hard into the lands then your gauge cartridge will be too long and you will actually be into the lands which may explain the marks.....ie they are into the lands and not off as you want.

    The OAL Case you are using, is this one made from one of your own Fire Formed Cases. If not you will have an immediate error in your measurements since the case shoulders are different. If you have a Headspace Gauge then measure your OAL Case then one of your Fired Cases and see what the difference is.

    No you should not see a mark on the bullet, make sure you hold the cartridge in line with the bore and against the extractor spring when pulling the bolt back or it will touch the sides of your chamber and leave marks.

    When you are working really close to the lands it's better to "Soot" the bullet with a lighter, candle or match as the soot is a lot easier to mark and gives you a better indication.

    Comment


    • Guest's Avatar
      Guest commented
      Editing a comment
      Ha! I knew I could count on you for a reply Mega! thanks

      the modified case is just a hornady one - not one of my own - just measured with an OAL case gauge (the fireformed case is 0.0027 longer) - at this point is it ok to simply keep re-sooting the bullet and seat the bullet 0.001 deeper until it doesnt touch the lands?

      I have a forster ultra micrometer seater (I assume the micrometer on top is reasonably accurate)

  • #3
    That's okay mate.

    So, problem solved. You are out by 0.003".

    Keep using your OAL case, it's a more accurate way to take the measurements and the more you get used to using the same touch on the bullet the better and you can keep a record of throat erosion.

    Lets see if I get this right. Your OAL case is 0.003" shorter than a Fire Formed Case so all your rounds you have made thinking they are 0.001" off the lands are actually 0.002" into the lands. You need to subtract the difference every time to get the correct figure. Actually there is even more because your fire formed case will be at least 0.001" or more short of your chamber length due to spring back on firing.

    The only way to check the micrometer top is to measure a seated bullet, then reduce the next one by what you think is 0.005" and see if it does measure correctly. Don't re do the first one as it's not the same as seating one from scratch with the bullet out of the case neck.

    OFFER......

    If you want a correctly sized OAL Case then send me two fireformed cases and I will make you a Gauge to suit your own chamber. The second case is just in case something happens to the first whilst turning in the Lathe. I will measure both cases to make sure they are the same. Now, it may take me a couple of weeks as I can only use a Lathe elsewhere at a neighbours (old fellow about 90yo) and he may not be available to let me into his shed.

    Will cost you postage both ways and whatever packet you put them in.

    Comment


    • Guest's Avatar
      Guest commented
      Editing a comment
      thanks Mega - thats a generous offer (I'll send you a couple cases + a paid return envelope if you PM/email me your address) - whenever is convenient for you is fine

      I'll try reseating some fresh loads and re-measuring as well

  • #4
    Email sent, just let me know when you have posted them as I'll need to check the mailbox out on the main highway. I'm restricting my driving as I'm just about out of fuel until next pension day and zero in the bank.

    Comment


    • #5
      Gday Boys,

      Mega thanks for Highlighting that about the fireformed case compared to the ones Hornady sell. I had never thought of that when measuring COAL in my calibers.

      When measuring for my .204 I can not even get the berger to sit in the gauge as the rod is right at the case mouth when I insert it into my chamber.

      Good to be back on mate.

      Comment


      • #6
        "butta9999" Pretty sure a long time ago that the .204Ruger liked a lot of "jump" and that's the way it was designed so finding the lands measurement is of no use to any normal shooter. With different twist rates and custom chambers maybe the much heavier bullets will work seated longer. I don't see much sence in using a 55gr or heavier bullet in a .204Ruger.

        It is ideal to make the OAL Gauge out of your own Fire Formed Case and BRT have offered this service for a long time as well as other custom reloading work.

        As long as you have a record of the case base to shoulder datum point measurement and use that difference when comparing your own case then it really doesn't matter but is a point where an error can easily be made if you didn't know or forget.

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        • Guest's Avatar
          Guest commented
          Editing a comment
          Gday Mega,

          Yeah I remember the information about the .204 shooting better with some free travel.

          My .204 is shooting well at the moment.
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