Wby Accumark Berger 300Gn Seating Issues

Discussion in 'Reloading' started by kc0pph, Feb 28, 2012.

  1. kc0pph

    kc0pph Well-Known Member

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    I have this Wby Accumark and when seating the bullets i have been running into some issues. I always set my bullets slightly shorter than the measurement i get via sticking a bullet in a fired case and closing the bolt. I then usually go about 15 thousands of an inch shorter than that.

    When i do this with the Wby the VLD barley seats past the boat tail. I believe this is because of the freebore but not sure.

    I hear a lot of individuals talk about seating .002" off the lands. How do i measure that in a 338-378?

    Berger Reccomends seating bullets .040 to .130" from the lands.

    I have never gotten into this part of reloading and cant imagine how to do this. I see a Horniday Tool but there is no 338-378 wby attachment for it (That i can see)...

    Anyone have any tips for how to accurately seat these bullets?
     
  2. Broz

    Broz Well-Known Member

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    The way Wby calibers get the extra velocity is the long freebore allowing a larger charge with out the pressure. You will not get to the lands with the factory 338-378 chambering.

    Try seating some about .020" shorter that your mag box length. Just short enough that they wil feed through the box and not bind even when angled.

    Then go buy the proper tool to measure o-give to case head in your non wby calibers.:)

    Jeff
     

  3. kc0pph

    kc0pph Well-Known Member

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    Well if i do that with the VLD's the tip of the case mouth would be on the ogive.
     
  4. Broz

    Broz Well-Known Member

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    The 378 case is 2.900 trim length right? ( I am going off memory here)

    The mag box should pass a OAL of 3.800"

    That is the best you can do unless you wish to single feed them.

    Jeff
     
  5. Broz

    Broz Well-Known Member

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    The freebore in your rifle is .361" if that helps you any.

    Jeff
     
  6. kc0pph

    kc0pph Well-Known Member

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    I am not at my reloading bench (its 10 miles away at the parentals house), and i dont have a case handy.

    I tried to seat to 3.750" (What berger sent me using quickload), and they were "Crimped" on the ogive. Not good.
     
  7. sp6x6

    sp6x6 Well-Known Member

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    You dont want to crimp, that has to do with die set up. I dont have a 338-378, but loaded a 340 for over 20+. You could single feed as Broz, suggest, I have a friend that carries a few "first shots''. But with seating you should find something to work. A comparator of some type will help you with adjustments. You can do the old fashion, cut channel in top of brass, slot w/small jewlwers or small hacksaw, press in slight to hold bullet. Run into chamber and pull out carefull, that will give length to lands, I use a Sinclair tool for this, but with you free bore most of this is a mute point because you want to fit mag. I load for several Weatherbys, and you just find what they like.
     
  8. bigngreen

    bigngreen Well-Known Member

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    The 300gr OTM has a hybrid ogive, it's not going to give you the possible fits that a VLD would, you should have a much broader range that the bullet will shoot well in.
     
  9. kc0pph

    kc0pph Well-Known Member

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    Well it was really windy today so no good results However i do know now that i need to set the shoulder back 3 thousands in order to get it to chamber freely. They are set to 2 thou currently. I seated them as deep as i could and still have the mouth sit on the bearing surface. They wont fit in the mag, but that does not bother me. Ill play around next non windy day ill see how these group.
     
  10. sp6x6

    sp6x6 Well-Known Member

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    I had a few issues where the berger indexed off the seating stem since bullet is so pointed and metplate varies, I clearanced my stem w/ drill, on a micro forester, this helped get my oal more consistent.
     
  11. dig

    dig Well-Known Member

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    Don't worry about the lands in the Weatherby's as others mention there is a lot of freebore and most shoot fine loaded just short of mag length say 20 thous, just make sure they feed. Also if this is a factory barrel I had a tough time with the heavy bullets the 250's shot better in a factory rifle also had to play a lot with powders.