Optimizing Quickload Data with Burn Rate and Bullet Weight Changes

Discussion in 'Reloading' started by RockZ, Apr 30, 2009.

  1. RockZ

    RockZ Well-Known Member

    Messages:
    899
    Joined:
    Mar 10, 2006
  2. AJ Peacock

    AJ Peacock Well-Known Member

    Messages:
    2,229
    Joined:
    Oct 7, 2005

  3. RockZ

    RockZ Well-Known Member

    Messages:
    899
    Joined:
    Mar 10, 2006
    I've been hoarding all of the good info for a while. I figure it's time to share. LOL
    Let me know how it works out.
    I've been able to tweak the values very close.
     
  4. kcebcj

    kcebcj Well-Known Member

    Messages:
    1,215
    Joined:
    Jan 28, 2008
    Good info. Thanks for posting.
     
  5. gbp

    gbp Well-Known Member

    Messages:
    227
    Joined:
    Aug 22, 2006
    Thank You !!!
     
  6. steve smith

    steve smith Well-Known Member

    Messages:
    244
    Joined:
    Jul 4, 2001
    Just purchased QuickLoad!

    I'm a little curious as to how much you guys are having to fudge the burn rate factor and bullet weight, to get Quickload to match your emperical data.

    Using all the cartridge dimensions, I'm able to get everything to match up by adjusting the burn rate factor, but the velocity will be off quite a bit when I reduce the charge wt. I've tried decreasing and increasing the bullet wt. a few grains to see if it would help, but I just can't seem to get the velocity to match up for two different charge wts.

    Also, what initiation pressure are you using, and for what situation (bullet seated .010" into lands, right at, or sitting out some distance).
     
  7. AJ Peacock

    AJ Peacock Well-Known Member

    Messages:
    2,229
    Joined:
    Oct 7, 2005
    I've never had a problem getting pretty darn close (within 1-2%) with just adjusting the overall length and the water capacity of the brass.

    What Chrono are you using?

    AJ
     
  8. steve smith

    steve smith Well-Known Member

    Messages:
    244
    Joined:
    Jul 4, 2001
    Competition Electronics ProChrono

    I know it's not the best, but it has been farely reliable, so long as everything is square and level.

    I played with the H2O capacity, but didn't think of adjusting the OAL!

    But! If you're only getting within 1-2% then I'm probably close enough.

    Guess I'm just being a little too anal. That's what I hate about Engineering Data, it's a very good approximation, but for someone like me (having a machining/fabrication background) being off 1-2% seems like a mile. It's a wonder, why I'm in school to become an engineer! I'm having to learn when to say "close enough".
     
  9. Autorotate

    Autorotate Well-Known Member

    Messages:
    503
    Joined:
    Apr 2, 2007
    IF well.
    Steve

    I've found the following technique to work for me......

    Go to range with 10-15 different powder charges using the same bullet/loading methodolgy (neck tension, primer, case prep, etc). For example....from the published starting load to the published max load for your case/powder/bullet combination in one grain increments it spans 12 grains. 83 grain starting load, and it ends at 95 grains. You'd load one bullet at each increasing powder charge. Record velocities from shot string.

    Then in QL, "build" the cartridge for your gun by

    1. Input actual water case capacity
    2. Input correct COAL
    3. Select powder
    4. Select temperature
    5. Input barrel length

    Once the cartridge is set, I adjust the case weighing factor and the start pressure in attempt to match my gun to the lowest charge velocity, and the highest charge velocity. I've found if you can get QL to model the 1st shot velocity and the last shot, it will predict the "steps" between the two on the increasing powder charges. (Remember to throw out your first few fouling shots as they will throw the velocity step/spread off)

    The reason for using the published data, is some reloading references list the specific pressure for a given velocity, and barrel length. Now every gun/throat/barrel is different, but that's an additional factor of analysis that you can compare with your gun. Example: your gun is a 26" barrel just as is listed in the published loading data. You achieve the max load velocity, but with two grains less than the max load. To assist in achieving an accurate model, try adjusting the case weighing factor/start pressure until QL achieves the same max pressure listed in published loading data for that specific velocity. After doing that, check the rest of the "steps" on the incremental loads and see if the velocities are matching up.

    If you have a different barrel length, be sure to correct for that when comparing published velocities/loads/pressures.

    Once you have the case weighing factor/start pressure down record it for future use. For example, I found with a 300 RUM 40 degree shoulder that .35 on the case weighing factor works well, and for .025 from lands, a start pressure of 8000 works in one gun of mine.

    Now using that same case weighing factor and start pressure, QL does a very accurate prediction of how other powders will perform.

    The start pressure doesn't seem to be a hard and fast rule, and seems to difficult to predict when changing neck tension or distance from lands.