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Thread: Q for those more expert than myself

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    Q for those more expert than myself

    I've just made up a batch for the (K) Hornet as I've got some mods to compare accuracy/grouping over the weekend.
    Checking COAL there's quite a variation which I suspect is down to the starting variation in the empty case length.

    My issue is that the empty cases are mainly already less than the SAMI std of 1.403"
    I've just checked 50 cases at random, only 4 were SAMI or longer with the rest ranging from 1.388" up, most are at 1.396/7/8.

    So the question is...should I trim them all down to a uniform size even though under the SAMI recommended, or would it be better to maybe re-set the seating die with a case of average mid size & accept some variation from the longer & shorter cases.

    Over to those more knowledgeable .

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    22 K Hornet COAL

    Quote Originally Posted by angrybear View Post
    I've just made up a batch for the (K) Hornet as I've got some mods to compare accuracy/grouping over the weekend.
    Checking COAL there's quite a variation which I suspect is down to the starting variation in the empty case length.

    My issue is that the empty cases are mainly already less than the SAMI std of 1.403"
    I've just checked 50 cases at random, only 4 were SAMI or longer with the rest ranging from 1.388" up, most are at 1.396/7/8.

    So the question is...should I trim them all down to a uniform size even though under the SAMI recommended, or would it be better to maybe re-set the seating die with a case of average mid size & accept some variation from the longer & shorter cases.

    Over to those more knowledgeable .
    Hi Angry Bear
    Case length should have no influence on COAL because it is determined by the distance from the seating punch contact point and the shell holder surface when the press ram is in the fully closed position. However, if the seating punch either deforms the bullet tip or somewhat deforms the bullet ogive (may be very difficult to see) then you will likely get differing COAL which is then related to seating resistance. This may of course be inter related with neck length, neck ID, brass hardness etc. I have had exactly the same problem as you with a number of calibres and bullet ogive forms. The last one I had was with my standard Hornet. I just made a nose punch to suit the bullet I use and problem instantly solved. Unfortunately I don’t know if you are able to do the same with what equipment you have access to.

    Cheers
    pjinoz

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    If you're using dies that rely on the neck meeting the die (lee combine crimp and seat die for example) then I can see how this would happen. I much prefer the dead length seater die as the shell holder meeting the base of the die is a definite stop and leads to more uniform loads.

    I would trim them all to the same length and load but do a couple of pressure loads at .5 / .2 gr under as you'll be eating up case capacity. Have they shrunk through fire forming?
    Thanks for looking

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    harry mac's Avatar
    harry mac is offline You can't say muntjack without saying mmmmm
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    Did you re-size the empty cases before measuring them?
    The South of England has 2 good things, the M1 and the A1. Both will take you to Yorkshire.

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    Quote Originally Posted by Boydy47 View Post
    If you're using dies that rely on the neck meeting the die (lee combine crimp and seat die for example) then I can see how this would happen. I much prefer the dead length seater die as the shell holder meeting the base of the die is a definite stop and leads to more uniform loads.

    I would trim them all to the same length and load but do a couple of pressure loads at .5 / .2 gr under as you'll be eating up case capacity. Have they shrunk through fire forming?
    I suspect so.

    Quote Originally Posted by harry mac View Post
    Did you re-size the empty cases before measuring them?
    Yes, neck sized, RCBS if it matters

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    Trim to uniform length and load in that case, RCBS seater works on the case mouth as the datum, if they're only 5 - 7 thou short then pressure shouldn't be an issue unless you're at max load.
    Thanks for looking

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    harry mac's Avatar
    harry mac is offline You can't say muntjack without saying mmmmm
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    Quote Originally Posted by angrybear View Post
    I suspect so.



    Yes, neck sized, RCBS if it matters
    It does matter. When a case is fired, it swells out to fill the chamber, this often has the side effect of shortening the case. If you only neck size, you won't squeeze enough of the case back into shape to make it "grow" again.
    measure all the cases and trim them all to the shortest length. At least then, you'll start with uniform case length.
    A few thou short of minimum is no bother. They will grow eventually, but neck sizing minimises movement of the brass.
    The South of England has 2 good things, the M1 and the A1. Both will take you to Yorkshire.

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    Quote Originally Posted by harry mac View Post
    It does matter. When a case is fired, it swells out to fill the chamber, this often has the side effect of shortening the case. If you only neck size, you won't squeeze enough of the case back into shape to make it "grow" again.
    measure all the cases and trim them all to the shortest length. At least then, you'll start with uniform case length.
    A few thou short of minimum is no bother. They will grow eventually, but neck sizing minimises movement of the brass.
    Cheers, AFAIK they only make neck sizing dies for the K Hornet .

    Another point I overlooked is that all these cases had also just been annealed, so I'll check again after fireing.

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