Question on Berger VLD Load Development

Discussion in 'Reloading Forum (All Calibers)' started by bsekf, Jan 5, 2019.

  1. bsekf

    bsekf

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    After studying the Berger VDL CBTO determination method, I've been doing load development ass backwards for 70 years and have some questions:

    How many use this method for bullet seating depth development? (CBTO) Do you think it works?

    Are you really doing seating depth development before load development (powder and weight)?

    Do you use the Berger method for all brands of bullets, not just Berger VLD?

    Do you find other brand low drag bullets are most accurate at about the same CBTO?

    Do you find all bullets are most accurate in a particular barrel at about the same CBTO?

    Bill
     
  2. Ned Ludd

    Ned Ludd Silver $$ Contributor

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    This approach is designed for use with a bullet, possibly such as a VLD, for which you may not have any idea at all where it wants to be seated. It covers a very wide range with a minimal number of shots to hopefully get you roughly dialed in to a particular seating depth region, where you will then test seating further in much finer increments. This approach is not without issues/considerations, such as markedly changing pressure due to the wide range of seating depth and effective decrease in usable internal case capacity. Personally, I would not choose to use this as the first approach unless I had no idea whatsoever where a bullet wanted to tune in or simply couldn't find an acceptable seating depth using a more typical approach.
     
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  3. JimSC

    JimSC

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    yes
    yes
    yes
    no, for my .223 I seat the Berger 80 .075 out, for the Sierra 80 I seat dead on the lands
    no, each bullet seems to have it's own preference as does each barrel.

    I am attaching a copy of a spreadsheet from a recent load development, for the load test using 120 SMK's and H4350 in a .260 Rem, 30 inch Shilen. Top to bottom is the order I shot it in. First a pressure check over the entire range of powder weights, then the seating depth test, and finally the load test. Notice I skipped 43.5 on the load development part becasue I used 43.5 for the seating depth test and already had good data

    At home I loaded the powder charges and seated the bullets into the lands. I carry a portable press to the range and after the seating depth test reseat the bullets to the optimum depth
    3rd firing.jpg
     
    Last edited: Jan 5, 2019
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  4. JMayo

    JMayo

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    Find a load, that works well at touching ...adjust seating to tighten up group.

    That's me ...
     
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  5. bsekf

    bsekf

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    I really thought I would start something with this post! Only one of the three replies use the Berger method, that's 30%, but not a very good sample.

    jmayo, your way is the way I've done it. I tried the Berger method with pretty good results with VLD's. Classic Hunters seemed to shoot well with any CBTO. Going to work up a 6BR and want to try Nosler RDF and Hornady ELD, I've a feeling they will be picky about jump, like the VLD.

    I can't thank the Berger organization enough for their technical assistance.

    Bill
     
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  6. Laurie

    Laurie

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    ........... and me.
     
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  7. powderbrake

    powderbrake Gold $$ Contributor

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    I start at touch(determined by the Wheeler stripped bolt method) and get best group powder charge, then adjust seating depth to get best group.
    I do this whenever I change lot numbers on the bullet as well. My last Lot of Bergers were .006 different in location with the stripped bolt test.
     
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  8. STOMP442

    STOMP442 Silver $$ Contributor

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    I start with a .025" jump and adjust up or down from there. Very rarely do I need to adjust anything, most of the time I can get a load shooting right there regardless of bullet brand.
     
  9. Joe Salt

    Joe Salt Silver $$ Contributor

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    Still have to say the easiest way is to start in the lands, then you only have one way to go! And don't be afraid to go back a 100 Thou. like berger says.

    Joe Salt
     
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  10. CharlieNC

    CharlieNC Gold $$ Contributor

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    Recently I had a new barrel installed to shoot 90vld in 223ftr. It was widely reported that this round is very sensitive to seating depth, and with a considerable range of results for what is best. So this is the first time I decided to evaluate seating depth first, as I wanted to have the best chance of clearly identifying the charge nodes. I did not use the extremely wide range suggested by Berger, because as stated this was not a completely undefined quest but an evaluation of which known results best fit my specifics. Using a moderate charge (again from reported results) the jump was clearly learned, followed by a single shot ladder because I had reason to have confidence in limited sample size. Followup fine tuning, including primer type, did not alter the initial results significantly. Long story to say I think the range of depths and approach depends of what is well known about your application.
     
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  11. Nature Boy

    Nature Boy Gold $$ Contributor

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  12. barefooter56

    barefooter56

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    Ned,
    In regards to the pressure issue. I always suggest that any bullet seating depth testing should be done using the starting powder charge listed for the bullet/powder/cartridge combination being tested. Once the bullet seating depth accuracy node is found. Then work the powder charge up slowly checking for pressure signs and accuracy until the highest velocity accuracy node is found. There are many ways of doing load development as we know. To me finding the bullet seating depth accuracy node first sets up the useable cartridge case powder capacity available to use before you hit pressure . Have had good luck using the "A to B" method over the years beginning with shooting PALMA . And full disclosure , I don't like sticking a bullet into the lands unless that is the only place the rifle likes it. An action full of powder when they call a cease fire on the line irritates me :)
    To each his own!
     
  13. Ned Ludd

    Ned Ludd Silver $$ Contributor

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    Phil,
    Powder charges listed in reloading manuals have little relation to real world loads used in competition such as F-Class. Unlike loads listed reloading manuals, most competition reloaders use significantly greater powder charge weights due to not being restricted to mag length, and that allow them to take advantage of long, heavy, high BC bullets. More specifically, many competitors often have a specific bullet (or class of bullets) in mind when they have the rifle chambered, and thus have the freebore cut accordingly. For that reason, there will usually be some restriction on how far they can effectively change seating depth without going outside the optimal window designed into the rifle's throat dimensions. If the freebore is cut to put a specific bullet at "touching" with the boattail/bearing surface junction seated approximately in the middle of the neck, then they will have about half the total neck length to move the bullet farther off the lands before the boattail/bearing surface will be seated below the neck/shoulder junction. The closer the boattail/bearing surface junction is to the neck/shoulder junction when the bullet is seated at "touching", the less overall range will be available.

    Like you, I don't ever like to put a bullet into the lands unless it absolutely won't shoot anywhere else. In fact, I have rarely found it necessary to do so, even with VLDs. I have also made some crude estimates of the increase in pressure from bullets seated into the lands. As far as I can tell, seating a bullet from about .005" or .010" into the lands should only raise the pressure by approximately 1000 psi or so. Unlike a "hard" jam of around .020" to .025", .005" to .010" into the lands is typically not enough to require a decrease in charge weight of even 0.1 gr. Nonetheless, I typically try to mention the notion of reducing charge weight slightly when seating bullets into the lands on reloading forums, just so people reading a thread will be thinking about it. As we both have noted, there is usually more than one approach to most reloading steps that allow one to end up at approximately the same place. It is up to the individual to find out which steps and in which order work best for them.
     
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  14. Zero333

    Zero333

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    I start with charge weight testing. With VLD bullets I start 10 thou in the lands (but not jammed) and with tangent ogive bullets I start at kissing the lands.

    Once I have the powder charge weight figured out I try different seating depths.

    If I can't find a good load with powder testing, then I try a different powder.
     
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  15. PatMiles

    PatMiles Gold $$ Contributor

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    Wouldn't 10 thou into the lands be jammed?
     
  16. Ned Ludd

    Ned Ludd Silver $$ Contributor

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    The term "jam" typically refers to a hard jam; i.e. the bullet is far enough into the lands that bolt closure will actually force the bullet to move farther into the case neck, not farther into the lands. A hard jam will generally be somewhere in the neighborhood of .020" to .025" or so into the lands.
     
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  17. PatMiles

    PatMiles Gold $$ Contributor

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    Thank you sir.
     
  18. Zero333

    Zero333

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    I define "jam" when I can't extract a live round because the bullet is wedged between the lands.
     
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  19. barefooter56

    barefooter56

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    I agree with what you are saying Ned. We have be well on the conservative side because we deal with shooters ranging from Hunters to Target shooters to weekend shooters with many levels of reloading experience from just beginning and up. That is where we are coming from. Crawl , walk , run. Safety first.
     
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