Jumping bullets a mile!

Discussion in 'Reloading Forum (All Calibers)' started by eric32, Mar 31, 2020.

  1. eric32

    eric32 Shooting when I can Gold $$ Contributor

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    So i ran across this article and wanted to get some of you smart guys thoughts on the data and results.

    https://precisionrifleblog.com/2020/03/29/bullet-jump-load-development/

    To me this makes sense considering the Nosler RDFs and Berger VLDs some guys are getting flyiers at traditional seating depths.

    I found great success at .050 jump in my 260rem for 800rds no change in accuracy.
     
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  2. Bc'z

    Bc'z Gold $$ Contributor

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    I'm no expert, but I've witnessed groups come in, go out, and come in agian during seating tests moving in .003 increments.
    I've personally never tried the berger method as I feel moving in .030 increments you'd possibly be jumping over your seating depth node.
    Just my experience I usually find my accuracy between .010-.015 off of touch.
     
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  3. divingin

    divingin

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    In my 6BR, the Berger 105 Hybrids seem to like a jump of about .030". I think I was running the VLD's at about .070", but never was really satisfied with consistency (hence the change to Hybrids.)
     
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  4. Alex Wheeler

    Alex Wheeler

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    I talked with Mark about his testing a few months ago. Keep in mind he is looking for the widest tune not necessarily the tiniest group. Thats not to say you may not also find the tiniest group at those jumps. Just know what his goal was with this testing. I do think he did a very good job of achieving it.
     
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  5. eric32

    eric32 Shooting when I can Gold $$ Contributor

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    Yes that was the goal the most forgiving load depth to resist chassing lands and diffrent evenviormental changes.But we traveling to matches whether LR BR or a Hunt. This info can help achieve a shooter not having to change and tweak every part of his load. Rather than shooting and learning the wind.

    Thus giving you the most stable rock solid load and you can take anywhere from the desert to the mountains and it will shoot. And that way you add a little whiggle room to the loading process.


    Do add some additional info

    Erik Cortina video of his group at 1k is ES was 18fps so wiggle room is needed for sure even with the best load.
     
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  6. Straightshooter1

    Straightshooter1 Gold $$ Contributor

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    After reading the article, it all sounds very good and logical, but I'm still trying to process (in my mind) all that's actually going on as the bullet is seated deeper at each interval. For example, if one is starting with a load that fills the case to something like 102% of case capacity when seated at the lands, how far can one keep reducing the the seating depth until there's a major pressure problem? If one is starting with a load that only fills 94% of the case capacity, then there's plenty of room to not have much worry about too much pressure as one seats the bullet deeper. This issue wasn't mentioned in the article. I know this process is really all about POI, but as a bullet is seated deeper and deeper, one is changing MV and pressure curves (given the same powder load). So to some extent, MV data can be telling you something too as it relates to POI, isn't it . . . ??? Or maybe it just doesn't really matter???

    I've got some more mulling to do. ;) :D

    Anyone else have any thoughts along this line?
     
    Last edited: Mar 31, 2020
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  7. eric32

    eric32 Shooting when I can Gold $$ Contributor

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    Yes i thought about that as well i am gonna guess they used a starting load. That would be a question for mark since he conducted the test.

    @Alex Wheeler are you able to ask mark for powder charge specs for the #5 test loads?
     
  8. Alex Wheeler

    Alex Wheeler

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    We dont speak on a regular basis. He did share the data with me and I thought it was very good. I personally wouldnt worry about his powder charges, your barrel will be different. Even barrels chambered from the same batch with the same reamer and the same components do not tune up exactly the same. Many times they are close, but with a different barrel, chamber, powder lot, bullet lot, primer lots, ext chances his loads will work for you is highly unlikely.
     
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  9. eric32

    eric32 Shooting when I can Gold $$ Contributor

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    I was thinking along the lines as a baseline to see if the load where 100% case fill then compressed when the seating depth increased. Or it was at 90% then seating depth.

    Just as a start point
     
  10. Straightshooter1

    Straightshooter1 Gold $$ Contributor

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    You're so right about those differences. But it's not about how his powder charge might work in someone else's gun. It's about how his process might work (or not work) with someone else's powder charge(s) . . . given that some powder charges may present restrictions to the process.
     
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  11. Joe Salt

    Joe Salt Silver $$ Contributor

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    I've had rifles that only wanted to be way off the lands, like 125 thou. some at sixty so at 15, off I've always say start in, then you only have one way to go. Don't think I've ever shot a compressed load so can't help you there. The one that shot with 125 off was my wife's H.G. and in 2009 she kick butt with in PA.

    Joe Salt
     
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  12. Alex Wheeler

    Alex Wheeler

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    From my experience powder charge will not drastically effect the correct seating depth. Meaning if you change your powder charge the gun will not go from preferring a .010 jump to a .060 jump. It may move a few thousandths but I think you can use any powder charge you want to rough in on seating depth.
     
  13. INTJ

    INTJ Gold $$ Contributor

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    Also, the father away from the lands we are the bigger the change in seating depth needs to be.
     
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  14. Homerange

    Homerange

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    My experience has been that the range of seating depths is very much caliber dependant. Small calibers are much more sensitive to pressure increases when seating deeper irrespective of the % of case fill.
    Large seating depth changes need be approached with caution and lessen the charge if necessary.
    Watch velocity and adapt the load to maintain a velocity sweet spot if you have one.
     
  15. dogdude

    dogdude Egan O'Brien Gold $$ Contributor

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    On the WSM, Joe Salt told me a few yrs. ago...''Don't be afraid to go eighty off''...mines shooting not too bad @ .081 off :), Thanks' Joe.
     
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  16. CharlieNC

    CharlieNC Silver $$ Contributor

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    Using a ladder approach for seating depth as well as for charge weight seems fine to me, but should be on the basis of horizontal movement in addition to vertical impact. I often see that vertical and horizontal move together in a manner which allows the node to be defined for both. Otherwise if selecting charge and depth based on vertical alone, what's left to tune the horizontal? The referenced example clearly showed shots 17-19 suited both, eventhough the discussion was only for vertical.
     
  17. garandman

    garandman Bolt Gun Bodacious Gold $$ Contributor

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    I'm at 0.010 off for my Berger 6.5 Hybrid Target 140gr and .224 80.5 FullBore Target and 85.5 Long Range Hybrids. Getting right at half MoA or a little bit less.

    And I been there for some 500 rounds.

    I find seating depth the old fashioned way.... 5 round groups starting at the lands and then at increments of 0.005 off as far as needed to group well.
     
  18. dogdude

    dogdude Egan O'Brien Gold $$ Contributor

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    G-man, starting in and going .005 is not old fashion..that's how every normal B/R guy does it, to one extent or another.:D
     
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  19. rckendall

    rckendall Gold $$ Contributor

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    I've had a 6BR that needed .125 jump because of the over-extended throat (gunsmithing error). I went with the 105 Berger boat tails and got great results.

    Now I am faced with the situation of loading for mag length (223). Should I start with max and reduce lengths first, before changing charge weights?

    Thanks for any insight,
    Richard
     
  20. eric32

    eric32 Shooting when I can Gold $$ Contributor

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    223rem with what bullet?
     

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