Bullet depth vs powder charge, which first?

Discussion in 'Reloading Forum (All Calibers)' started by X-47B, Jul 22, 2018.

  1. X-47B

    X-47B X-III:XVI Gold $$ Contributor

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    So I am developing a load for my rifle. And just got majorly confused. I am under the assumption that I have to figure out my powder charge before my bullet depth, but when I figure that out, I will then have to figure out my bullet depth which will change my powder charge??!! And if I do start with the powder charge; my CBTO is 2.255to the lands. I was gonna set the bullet back to 2.245. Is that a good place to start to get my powder charge?
     
  2. Clancy

    Clancy Silver $$ Contributor

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    I’ve started doing them both together as a starting point...

    I’ll load 12 rounds, shoot 10 and clean the new barrel, then shoot two foulers and start the following.

    For steel bangers and hunting rifles, I’ll load 10,20 and 30 off the lands, with a low medium and high but presumably safe powder charge.

    I don’t shoot BR, but I think most of them will do the same but with the bullet seated 4, 8 and 12 into the lands.

    Someone a lot smarter than me came up with all of this, but I can’t remember who.

    ***

    If I have shot the same bullet in several barrels, and it like the same seating depth, then I’ll just start the bullet there and shoot a bunch of different charge weights looking for a good wide node.

    But, if you don’t want to do all that, starting 10 off isn’t a terrible idea.
     
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  3. Canadian bushman

    Canadian bushman Silver $$ Contributor

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    I have had good luck with doing a couple coarse ladder test to give me an idea where the maximum charge is, and to see if there are any obvious nodes.

    Then i will do a coarse seating depth test at the highest powder charge that shot good, again looking for an obvious depth that stands out. Usually close to the lands, and into a light jam. I like as much powder capacity as i can get.

    After this i will do a few fine ladder test to try to get right in the middle of the sweet spot.

    Last will be very small seating depth changes, and groups shot at distance to tighten up grouping.
     
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  4. mikecr

    mikecr

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    IMO, seating is the coarse adjustment, and it does no good to move on to a fine adjustment (powder) without first putting seating in a logical place (at least near best).
    Also, if you attempt full seating testing from a powder node, then it will not take a lot of seating adjustment to collapse the powder node, causing 2 changes at once and masking best seating.
    Unless shooting an underbore or other cartridge where best seating is known and/or providing high starting pressures, then it works to just do Berger's full seating testing as written, step by step. This is at a reduced charge, and can be done during fire forming of brass, which has to be done before moving to powder anyway.
     
  5. brians356

    brians356 Gold $$ Contributor

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  6. brians356

    brians356 Gold $$ Contributor

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    Dan, study the targets, and Erik's commentary. The smallest group in this kind of "sparse" testing is not necessarily the best choice. It's the vertical shifting of POIs, or rather lack of it, that serves to suggest a "node" where the whipsawing barrel is most quiescent. The charge tuning serves to suggest a node, and the jump tuning is more likely to tighten the groups.
    -
     
  7. Puzzaz01

    Puzzaz01 Gold $$ Contributor

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    I'm with mikecr on his advise. I've been doing it this way and it works very well. First find a seating depth that gives you a good type group ( use flags) then try different powder loads. I know it sounds wrong but it works. I'll give you an example...... choose 3 different powder charges low, medium and high, now load 3 low charges at or in the lands, 3 at .010 jump, 3 at .015 and keep going in .005 jump for however many you want from a jam to about .035 jump and do this with all 3 charges and BAM the light will come and you'll see the group that you work with instantly.

    Darrin

    PS
    Don't let this secret get out...... lol.
     
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  8. Richard Coody

    Richard Coody Silver $$ Contributor

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    The charge tuning serves to suggest a node, and the jump tuning is more likely to tighten the groups.

    that is what i have found
     
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  9. Clancy

    Clancy Silver $$ Contributor

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    So what do you do when you start with a seating depth and it doesn’t show any promise at all? Now you’ve got to backtrack, do a seating depth test and then redo powder??

    Safest bet is on doing them both at the same time, or starting with seating depth.
     
  10. Canadian bushman

    Canadian bushman Silver $$ Contributor

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    If you plan to do seating first on a brand new barrel, how do you know how much powder to use?
     
  11. Clancy

    Clancy Silver $$ Contributor

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    I think it would be obvious that you’d pick a mild load and use that?? Not sure what you’re getting at.
     
  12. Canadian bushman

    Canadian bushman Silver $$ Contributor

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    I just dont understand how to do a seating depth test with a mild load, thats not in a node, without some sort of powder test first.

    How would you know if you are not in a node? How would you know you are far enough away from max to test a jam?
     
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  13. BenPerfected

    BenPerfected Gold $$ Contributor

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    Where does making small adjustments with a tuner fit in with SD & powder load?
    Ben
     
  14. Richard Coody

    Richard Coody Silver $$ Contributor

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    i believe in doing one thing at a time. when you change more than 1 variable you have no way of knowing which one actually resulted in the change you are seeing on the target.

    i do powder charge first looking for a node with the least vertical change on target with 2 or more different powder charges. powder charge will start in the middle of the reccomended charges for that powder and bullet. seating depth for this test will be hard jam for bench guns and .010 off or mag length for hunting/repeater rifles.

    seating depth follows. bench guns starting hard jam back off .005 increments. others .010

    after finding seating depth fine tune powder charge 5 five shot groups -0.6 -0.3 0.0 +0.3 +0.6

    then fine tune seating depth same way -0.06 -0.03 0.0 +0.03 +0.06
     
  15. Clancy

    Clancy Silver $$ Contributor

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    It doesn’t matter at all if you are in a node or not, the best rough seating depth will usually be very clear regardless of powder charge because you are just testing the seating depths against each other and nothing else matters at that time.

    Common sense would easily govern whether you were far enough from max to test a hard jam. For example, in my 6.5, I started two full grains below my gunsmith’s popular accuracy load.

    I know this is literally rocket science, but they’re tiny little rockets....
     
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  16. urbanrifleman

    urbanrifleman Site $$ Sponsor

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    Seating depth first. There will be seating depth that shoots better at all powder charges.
     
  17. Clancy

    Clancy Silver $$ Contributor

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    [​IMG]
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    Case in point.... here’s a complete waste of components searching for a very rough powder charge (no I don’t usually skip around a grain just needed something to shoot a few pigs with, one time deal.) bullets were seated .010 into the lands to show pressure if there was any.

    As you can see, changing seating depth was a whole lot more helpful. This is usually the case....
     
  18. ClassCat

    ClassCat Unlimited Gold $$ Contributor

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    Knowing your components. I shoot a bullet that i make. With my reamer and that bullet 90% of the time 12 off the hard jam works. I have about 8 powders that i shoot on a regular basis, and i know what each will do and how much will work given the ambient temperatures and conditions. Everything i do is documented in hard copy and in my brain.
    There is NO Substitute for experience.
     
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  19. damoncali

    damoncali Bullet Maker Site $$ Sponsor

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    In my experience, seating depth matters more than charge weight. I start jammed and work backwards. I have not found that a seating depth that is best at one charge is the best at other charges, but the difference is usually small. Bottom line is that if you want to nail it down for both, you've got to test both in various combinations.
     
  20. JimSC

    JimSC

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    never change more than 1 variable at a time in when testing or it impossible to know which variable you changed contributed to a change in the test results
     

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