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Thread: Different casings affecting seating depths?

  1. #1
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    Different casings affecting seating depths?

    Guys, I am new to the relaoding game and experimenting with the press and dies etc.
    I have used the lock-n-load gauge and comparator (0.308) and obtained the distance to the lands/ogive etc and therfore the required bullet (ogive) length.
    Now my question is, does using differing manufactures brass casings affect the desired bullet seating depth or is there something I am doing wrong?
    I have some Winehester brass and get 90% consistency in seating depth, however, when changing over to Privi and Federal brass, without changing any set up I have, the bullet seating depth is quite a ways off.....any advice greatly appreciated.
    Thanks, Jd.

  2. #2

  3. #3
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    Muir, I have measure COAL to be 2.284, backed off to 2.264 for the jump, this is what I set die for on the Winchester casings, then when using PP and Federal the seating depth is much greater, COAL in the region of 2.235 to 2.245 dependant on whether it was a Privi or Federal (all once fired cases). Maybe this is acceptable QA but I would have thought the tolerance to be a little tighter than that.
    Thanks, Jd.
    Last edited by oilmanjd; 12-01-2011 at 13:52. Reason: wasn't a clear description of Federal and Privi

  4. #4
    They should be tighter. That is too much. Are you certain that you have the does set correctly? It should be within a few-four thousandths.~Muir

  5. #5
    Are you using the "ogive length" for the COAL values you report, or are you using the bullet tip? If you are using the ogive length, then "something's rotten in Denmark". There's no mechanical mechanism for changing the OAL if the bullet doesn't change. HOWEVER, is there a possibility that you have mixed batches (lots) of bullets or even manufacturer? Different lots of bullets CAN have slightly different ogives, and small ogive-angle differences make big ogive length differences. Second, different bullet manufacturers OR even bullet types within a manufacturer WILL have VERY different ogival lengths.

    So...

    1) Are we discussing changes in ogival lengths OALs or "tip" OALs?
    2) Have you mixed batches of bullets (same type but from different boxes)?
    3) Have you mixed bullet types - flat-base for boat-tail for example, or 150 for 130?
    4) Have you mixed bullet maufacturers?

    These differences in OAL are too great IF the the ONLY component changed is the bullet, AND if you have not mixed batches of bullets.

    Regards,
    Paul

  6. #6
    Just a thought Paul - Muir , and I might be 'way-out here. If the different cases are of harder brass or have thicker necks, but the bullets are all of the same manufacture and model but the ogives fairly soft, might this cause the bullet seater to require to exert more pressure and dig in or distort the ogive a bit, thus giving a slightly different seating depth.
    The average bullet seater is not shaped to conform with every ogive pattern, and in some instances the push might be on the tip of the bullet whilst in others it will be the leading edge of the 'cup' which will force the bullet home.

    I've seen ring marks left in bullet ogives before now.

    Do you think that there's any possibility of this ?

    Ken.
    Last edited by ecoman; 17-01-2011 at 17:09.
    Opinions often differ according to unknown circumstances.

  7. #7
    Ken

    Spot on. The neck geometry is different and the neck tension is different.

    Regards JCS

  8. #8
    Quote Originally Posted by ecoman View Post
    Just a thought Paul - Muir , and I might be 'way-out here. If the different cases are of harder brass or have thicker necks, but the bullets are all of the same manufacture and model but the ogives fairly soft, might this cause the bullet seater to require to exert more pressure and dig in or distort the ogive a bit, thus giving a slightly different seating depth.
    The average bullet seater is not shaped to conform with every ogive pattern, and in some instances the push might be on the tip of the bullet whilst in others it will be the leading edge of the 'cup' which will force the bullet home.

    I've seen ring marks left in bullet ogives before now.

    Do you think that there's any possibility of this ?

    Ken.
    It's a possibility that what you describe could be a contributing factor but I doubt it could account for .020 to .030" of seating depth variance. I would venture that a variance in neck tension combined with linkage slop might account for a bit of variance. It just seems to me that this is excessive. I once tested bench mounted gear against the Lee Classic (In line) loader and found that with same lot brass for both (simultaneous loading starting with new brass) the bench gear averaged +/- .006" over-all-length with over the counter bullets, and the Lee in line averaged +/- .003 inches. ~Muir

  9. #9
    Exactly what Muir said including the measurements.

    While my sources and circumstances were different, I find it almost impossible, even with a "micrometer die" to consistenty do better than about 0.003", and for most dies, 0.005" in ogival length.

    The source of that variance is tedious to ascertain. It can have a variety of origins including all you mention.

    Regards,
    Paul

  10. #10
    Thanks both - just a thought. I'll add that the 'dents' were more often seen in round nose bullet models.

    Cheers Ken.
    Opinions often differ according to unknown circumstances.

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