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Thread: Press Runout?

  1. #1

    Press Runout?

    I have a RCBS rock chucker supreme press. The ram visually doesn't seem to be aligned with the centre of the hole where the die goes.

    After recently buying a decent concentricity gauge I checked the neck runout on some new 6.5 x 284 Lapua brass which was 0.001" - 0.002". I necked up to 7mm using a 21st Century expander die and the runout increased to +0.006"

    I also reload .243 Win on the same press and get a fair bit of runout on the necks and bullets using Hornady New Dimension dies. +0.015" bullet runout in some cases.

    I know that the dies aren't the best of dies, but with the ram being noticeably off centre I'm thinking that this is most likely the cause of the problem.

    Is there a way of adjusting the press or a way to make the shell holder self centre to the die? I'm planning to upgrade to an arbour press and wilson dies in the near future for resizing and bullet seating the .243 and .284, but I want to reduce the amount of runout during the necking up of the 6.5 x 284 brass as it seems excessive.

    Any thoughts would be much appreciated. Thanks in advance

  2. #2
    Find a friend and try running your dies and brass through his press and see what results you get might be a useful thing to do next. Regards JCS

  3. #3
    Quote Originally Posted by Jax View Post
    I have a RCBS rock chucker supreme press. The ram visually doesn't seem to be aligned with the centre of the hole where the die goes.

    After recently buying a decent concentricity gauge I checked the neck runout on some new 6.5 x 284 Lapua brass which was 0.001" - 0.002". I necked up to 7mm using a 21st Century expander die and the runout increased to +0.006"

    I also reload .243 Win on the same press and get a fair bit of runout on the necks and bullets using Hornady New Dimension dies. +0.015" bullet runout in some cases.

    I know that the dies aren't the best of dies, but with the ram being noticeably off centre I'm thinking that this is most likely the cause of the problem.

    Is there a way of adjusting the press or a way to make the shell holder self centre to the die? I'm planning to upgrade to an arbour press and wilson dies in the near future for resizing and bullet seating the .243 and .284, but I want to reduce the amount of runout during the necking up of the 6.5 x 284 brass as it seems excessive.

    Any thoughts would be much appreciated. Thanks in advance
    That's the answer to the 243 question. Also, FL resize that necked up brass and see what you get. That doesn't seem out of place to me as necking up is not a sizing operation, it is a mid stream forming operation that isn't complete until the case is run into a sizing die.

    I have seem RCBS presses made. They are line bored. Where does the 'visibly off center' manifest itself?~Muir

  4. #4
    Thanks chaps.

    Will full length sizing correct any runout in the both size cases? I'm only neck sizing the .243 at the moment as the .284 is in the process of being built.

    I'm going to neck turn the .284 and .243 brass on a 21st century lathe. Will the runout affect neck turning or will the slack in the lathe compensate for the runout? Presumably as long as the neck is tight on the arbour it would be ok and then full length sizing would correct the case?

    I will post a photo ASAP of the press to show where I think I can see that the ram is off centre.

    I tried the Hornady lock n load quick change bushings in the press a while back, but wasn't a big fan. Could I have messed up anything when reinstalling the standard RCBS threaded bushing?
    Last edited by Jax; 26-07-2014 at 07:53.

  5. #5
    The fit of the shell holder and how well it was made could easily account for you run out. As could the chambering on your rifle ............................. Nooooooooooooooooo oh the shock horror!

    There will some clearance in the thread and the bushing so yes you could have introduced this problem.

  6. #6
    im home now
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  7. #7
    As you can seem from the image, the shell holder doesn't appear to be centred or is this normal? I tried the shell holder in various positions, but there is always a bigger gap at the 6 o'clock position where the shell holder slides in.

    Could it be worth me removing the clip that keeps the shell holder snapped in tight to see if that helps with the runout when necking up?
    Attachment 45061

  8. #8
    Probably a daft question - but have you meticulously cleaned your shellholder especially the part that holds the rim of the case? You would be surprised how little amounts of crud can throw out the aligning of the case.

    When you get your Wilson press and dies you will wish you had got them ages ago - you will never have to look at another make of die.

    Peter

  9. #9
    jax ring us mate
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  10. #10
    Practical Precision Reloading - utilising this procedure may help.

    Quote from the article: With the case out of the shellholder, screw the die into the press. If it’s a neck-sizing die, you can probably bump the die with the shellholder. If it’s a full-length sizing die, a machined washer may be required between the die and the shellholder for correct die setting. The idea is to have the ram exerting pressure on the die at the time you tighten the lockring. The coarse 7/8×14 threads on the die and in the press head have enough play that locking the ring without a load on the die often results in tipping the die out of alignment with the shellholder.If you’ve followed these instructions, your ram, shellholder, and die should be in line. But you need to center the decapping rod in the die. To do this, run a case up into the die, then loosen the rod locknut. Withdraw the case far enough that the expander ball is in the neck of the case. Holding the rod under tension, tighten the locknut securely. The decapping rod should now be centered.
    Read more: http://www.shootingtimes.com/ammo/am...#ixzz38vjdAcRr
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