Problems getting good measurement trimming brass

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  • AKM

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    I'm trying to trim 308 brass and I'm getting from 1.995-2.015 on average sometimes up to 2.060 on the same casing. There's a small wobble in the brass while it's trimming, but I've read the trim pro 2 does that. Any ideas? I've gotten 3 out of 12 pieces that are right.
    DK Firearms
     

    robertc1024

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    Wow! That is a huge variation. I've got one of the Lyman ones that's similar and I consistently get them within 0.0015" Are you using the correct bushing that goes in the case mouth?
     

    AKM

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    Wow! That is a huge variation. I've got one of the Lyman ones that's similar and I consistently get them within 0.0015" Are you using the correct bushing that goes in the case mouth?
    Yes, the 223 brass I trimmed before was fine.
     
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    orbitup

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    I use one of these. It's a little easier to get consistent readings.

    https://www.midwayusa.com/product/584824/hornady-lock-n-load-bullet-comparator-anvil-base-kit


    584824.webp
     

    ScS

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    I'm trying to trim 308 brass and I'm getting from 1.995-2.015 on average sometimes up to 2.060 on the same casing. There's a small wobble in the brass while it's trimming, but I've read the trim pro 2 does that. Any ideas? I've gotten 3 out of 12 pieces that are right.

    Check all of the adjustment screws one more time. I had one back off once and got similar results to yours.
    The Trim it 2 indexes off the shoulder so the OAL could be different, while the measurement from shoulder is spot on. Could be different shoulder setbacks during resizing.
     

    AKM

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    Check all of the adjustment screws one more time. I had one back off once and got similar results to yours.
    The Trim it 2 indexes off the shoulder so the OAL could be different, while the measurement from shoulder is spot on. Could be different shoulder setbacks during resizing.
    im using a rcbs trimmer it holds the case rim.
     

    ScS

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    The holder sucks

    I don't really know anything about your trimmer, but somebody here does and will eventually help you out.
    I would at least for now cut them all down to a same usable length, even if I had to remove the cutter and do it freehand somehow.
     

    robertc1024

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    .015 isn't a deal breaker, it will work. But I would consider it excessive, and try to find the cause.
    Yep. I suppose it depends on what you want the ammo to do. For plinkers, it's probably fine. For shooting groups, no way.
     

    AKM

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    Have you called RCBS? They are excellent about helping out and even replacing their parts for free if there is an issue.
    Not yet, trying to figure it out before I go that route.

    I'm getting between 1.990-2.010 on average. This is for 600 yards. Feel like I wasted 60 pieces of brass
     

    Vaquero

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    Not yet, trying to figure it out before I go that route.

    I'm getting between 1.990-2.010 on average. This is for 600 yards. Feel like I wasted 60 pieces of brass
    Where did you get the brass? I've had some "once fired" brass that wobbled pretty bad in the trimmer. I suspect I got some machine gun stuff.
     

    baboon

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    I have an old Trim Pro with a different collet system to hold the base of the brass. I actually have a trim pro II & choose not to use it. I have done lots of .308 on mine. I have noticed if I crank down on the collet or even push real hard while turning the handle I got huge variation too.
     

    Charlie

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    Not yet, trying to figure it out before I go that route.

    I'm getting between 1.990-2.010 on average. This is for 600 yards. Feel like I wasted 60 pieces of brass
    I don't hesitate to call RCBS when I think I have a problem. They are great folks to deal with and understand exactly what I'm talking about. Give them a call.
     

    popper

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    Is it the trim pro 2? I have a lyman version, check for a bushing in the crank side that moved (thrust bearing that is also the stop). Also check that the case head holder is clean. Never did any for the 308, just BO.
     

    xdmikey

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    Sorry to hear that Mike.

    I have a trimpro, 1 or 2 I don't know but it seems to work well although I haven't measured lengths after trimming, that I remember.

    I'm also loading LC once fired but just prepping at this point.
    I will measure a random sample of my brass to see how things look.
     
    Every Day Man
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