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Thread: Any short cut tips on bullet seating depth

  1. #1
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    Any short cut tips on bullet seating depth

    Hi Lads.
    243 hornady 75g v-max heads, done the powder weight testing arrived at 43.5 gn of Ramshot big game.
    With a bullet seating depth of 2.640 im getting two shots within 1/2" with the third at 1 1/4" that is random -------suppose this needs more work ?
    From 2.640 - 2.745 which is around the maximum length i can go while still keeping 6mm in the case neck there would be 22 setting at 5 thou, i dont fancy doing all them shots, can anyone suggest any ways to reduce this, ie with the 2.640 seating depth doing 1 1/4" group, does this suggest it just need 5-10 thou either side of this ----or doesn’t it work that way ? -------am i better starting at 2.745 and reducing by 5 thou until i hopefully get there.

    Thanks for your help Dave (warbucks)
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    imagine an hour glass ,your seat depth will go in and out of nodes. work both ways in 5 tho increments one way shorter or longer should show promise.using 3 shot groups chase in 5 tho inc till it starts opens again.then fine tune in smaller increments. 1.5" i would check i'm using a good powder bullet combo.seat depth i doubt will tune that in to sub .50 but i could be wrong.by going longer at least when they tighten you can just seat the ones not used further in the case.i would expect to find a node within 30 tho.

    mike

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    3 shots aren't a useful group, you need 5-10 to really get an idea of the group spread and size, sort out what is causing the flyer (if any once you go to larger groups) changing the cartridge length isn't going to fix problems with technique or the rifle setup
    Last edited by kennyc; 22-09-2018 at 10:40 AM.
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    Quote Originally Posted by kennyc View Post
    3 shots aren't a useful group, you need 5-10 to really get an idea of the group spread and size, sort out what is causing the flyer (if any once you go to larger groups) changing the cartridge length isn't going to fix problems with technique or the rifle setup
    so when you do your load development you do 5 to 10 shots each powder charge and then 5 to ten shots each seat depth ? 3 shot groups are fine to scan for optimum powder charge and seat depth. then when you find those nodes fine tune with 5 shots.

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    Thanks lads.
    Knowing that i should find the node within 30 thou helps.
    I have 6 made up round left ive reduced then by 5 thou and 10 thou, ive then made up some more at 15 thou off the lands and can progressively re seat them at 5 thou increments.
    The rifle, night vision scope and the man have repeatedly had 3/8"/10mm groups at 100 yds with Hornady 58g v-max, so nowt wrong there ------just need to get the 75g v-max to group a bit better.

    Thank you all for your help Dave (warbucks)
    Last edited by warbucks; 24-09-2018 at 11:17 AM.
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    Its generally recognised that the powder is the first step followed by the distance from the lands.

    My advice for a 'short cut' would be to use the OCW method whereby you start with a uniform distance from the lands ( I would suggest 40 thou back) for the weights of powder you have selected when using the 75 gr V max. If you move up in .3 gr increments you should find a node from the OCW target that is good and if you feel there could be improvement then stay with that powder weight but alter the distance from the lands to see if there is a change for the better.

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    Quote Originally Posted by warbucks View Post
    Thanks lads.
    Knowing that i should find the mode within 30 thou helps.
    I have 6 made up round left ive reduced then by 5 thou and 10 thou, ive then made up some more at 15 thou off the lands and can progressively re seat them at 5 thou increments.
    The rifle, night vision scope and the man have repeatedly had 3/8"/10mm groups at 100 yds with Hornady 58g v-max, so nowt wrong there ------just need to get the 75g v-max to group a bit better.

    Thank you all for your help Dave (warbucks)
    In my .243 I always found the 58gr vmax more accurate and better grouping than the 75gr vmax.

  8. #8
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    Quote Originally Posted by zx10mike View Post
    so when you do your load development you do 5 to 10 shots each powder charge and then 5 to ten shots each seat depth ? 3 shot groups are fine to scan for optimum powder charge and seat depth. then when you find those nodes fine tune with 5 shots.
    nope but the OP isnt asking for that though is he ? he has a group that isnt a group, he has no idea if it is representative or if he or the rifle is the problem,
    I use 3 shot groups to check speed and for pressure signs, and as a quick zero check before heading out, but if you want to know if a load is good enough to bother with dithering about with length you need to fire at least 7 rounds to get a good average dispersion.
    start at the basics, set to mag length, chose a starting powder charge, work that up in 3 shot stages (group size is irrelevent at this point) until you get the speed you want or pressure signs, then shoot some 7 shot groups, using those to fine tune your powder charge, once you are happy with that if you wish you can start playing with length, this is pretty much what you were saying anyway
    Last edited by kennyc; 22-09-2018 at 05:07 PM. Reason: removed part that was for another thread D'oh!
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    Quote Originally Posted by zx10mike View Post
    so when you do your load development you do 5 to 10 shots each powder charge and then 5 to ten shots each seat depth ? 3 shot groups are fine to scan for optimum powder charge and seat depth. then when you find those nodes fine tune with 5 shots.
    If you're finding optimal weight and length with 3 shot groups what is there left to fine tune with a 5 shot group?
    Thanks for looking

  10. #10
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    Im using big game in the .243 I don't use the 75grn vmax I found they weren't that good I now use 70grn serria blitzking with 40grn of powder seated to 2.617" but that's in my gun I found out that more powder made the group open up

  11. #11
    Eyefor is offline The Artist Formerly Known as Maple
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    Quote Originally Posted by warbucks View Post
    Hi Lads.
    243 hornady 75g v-max heads, done the powder weight testing arrived at 43.5 gn of Ramshot big game.
    With a bullet seating depth of 2.640 im getting two shots within 1/2" with the third at 1 1/4" that is random -------suppose this needs more work ?
    From 2.640 - 2.745 which is around the maximum length i can go while still keeping 6mm in the case neck there would be 22 setting at 5 thou, i dont fancy doing all them shots, can anyone suggest any ways to reduce this, ie with the 2.640 seating depth doing 1 1/4" group, does this suggest it just need 5-10 thou either side of this ----or doesn’t it work that way ? -------am i better starting at 2.745 and reducing by 5 thou until i hopefully get there.

    Thanks for your help Dave (warbucks)
    DEFINITELY load then length.

    Quote Originally Posted by dicehorn View Post
    Its generally recognised that the powder is the first step followed by the distance from the lands.

    My advice for a 'short cut' would be to use the OCW method whereby you start with a uniform distance from the lands ( I would suggest 40 thou back) for the weights of powder you have selected when using the 75 gr V max. If you move up in .3 gr increments you should find a node from the OCW target that is good and if you feel there could be improvement then stay with that powder weight but alter the distance from the lands to see if there is a change for the better.
    A considerable time ago (and after a serious amount of frustration with one particular 22-250) I followed Mr Dicehorn's advice and finished up with a home brew that sat -137 thou off the lands that was simply fabulous.

    Once you have found the load, make up 50 rounds at mid level OAL (as above, 40 thou) and then go to the range with your press and dies, fire five rounds, squeeze the next 5 rounds in 5 thou and repeat.

    Stick with it. It is worth it.

    PS (x2)

    1. Batch weigh the v-max (some awful variations)

    2. Ditch the v-max and switch to Sierra's
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  12. #12
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    Quote Originally Posted by 223AI View Post
    If you're finding optimal weight and length with 3 shot groups what is there left to fine tune with a 5 shot group?
    well once your are close you will be down to the .2 of a grain powder and 1 tho seat depth change.not sue you would want to do that on every charge and seat over a wide margin.

  13. #13
    Parabuteo is offline My Chrony has bought it a couple of times...
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    Nodes are based on more than OAL. It is to do with the points at which the barrel vibrates at the highest freq (so lowest amplitude). Node will depend on all sorts, barrel thickness, length, materal, charge, hold etc etc.

    This is why people shoot a ladder test/load test, then fine tune with the OAL.
    I'm a maggot in another life you know

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