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Thread: Seeking a source of load data for bullets cast from an MP mould

  1. #1
    Boolit Bub
    Join Date
    Sep 2017
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    44

    Seeking a source of load data for bullets cast from an MP mould

    Greetings!
    I have recently purchased an MP gang mold that is casting a 9mm 135gr FRNBB bullet, which will be powder coated. Needless to say, the Lyman Cast Bullet Handbook (4th ed) doesn't show data for this bullet in 9mm Luger, but it does show data for the 140gr SAECO and Lyman's 147gr TC. I am rather confident that I could begin with the starting charges for either bullet and work up. However, I was hoping that there might be a source of published data for this bullet.

    Can anyone point me in the right direction?

    As always, thanks in advance for your help!

  2. #2
    Boolit Master


    Join Date
    Oct 2010
    Location
    Franklin, TN
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    You Sir, are on the right track. You won't find any published data specifically for the MP bullet. Proceed as you have suggested.
    Take care, and good Luck,
    Rick

  3. #3
    Moderator


    Minerat's Avatar
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    Jun 2008
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    Many times finding published loads for cast bullets is a exercise in futility. I usually worry about weight and then look up loads in one of the cast bullet handbooks and find 2 similar bullets with weights above and below the one I'm loading for. I then pick the powder I want and use a starting load that is half way in between them. Then back off 10% to start a load work up.

    In most cases I have found that your working max load for the new cast bullet will be somewhere between the min and max for the heavier bullet. Bullet weight plus or minus 5gr will not have much effect on the powder weight\pressure unless you are working on maximum loads. Since I am usually 2 to 4 grains below max powder charges I don't worry about weight so much as long as they are close.
    Steve,

    Life Member NRA
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  4. #4
    Boolit Master
    Join Date
    Mar 2011
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    Western, MO
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    Don't forget to see what the bullet weighs after powder coat. Depends on lead mix, mold, heat and pc. It might be 140.

  5. #5
    Boolit Master
    Join Date
    Feb 2021
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    1,013
    I record the total bullet length of every bullet I use in reloading, along with the OACL. I also try to find bullet lengths for those I have not loaded, but for which load data is available. When using a new bullet, especially of equal or lesser weight, I measure the length of the new bullet and adjust OACL so that the distance between the primer and base of the bullet is the same (i.e. internal volume available for powder combustion is the same).
    *
    Of course, more factors are involved.

  6. #6
    Boolit Buddy
    Join Date
    Jan 2008
    Posts
    144
    I'm pretty sure that m&p mold is well liked here, but most shoot it as a hollow point. If you supply the mold number, some around here might be willing to share what has worked for them. Also, keep in mind the 140gr SAECO #383 has very little bullet in the case. The bullet you have likely use more of the power space despite weighing less.

    I've found a chronograph to be amazingly useful as my velocity rarely seems to jive with a lot of reloading manuals. If you don't have one, it is a wise investment with cast where you rarely have exact data and since different sources seem to contradict each other so often.

  7. #7
    Boolit Grand Master
    rintinglen's Avatar
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    I have oodles of molds--please excuse the technical term--and the vast majority have no published data for them. Yet I have managed over the last 50 years to cast and load well over 100,000 rounds of ammunition. How, by doing exactly what you propose to do.

    Namely, I find a bullet of similar construction and weighing roughly 5% heavier or lighter. Then I use the starting data for the 'official" bullet for my start and work up gradually, .1 or .2 grains at a time to a load that either meets my accuracy standards or equals 95% of the max charge listed. I load my boolits to the heavier bullets COAL. Most of the time, I will be at or very near the midpoint between the min and max. I don't generally go near the top. Save for hunting loads, I have never found the need.
    _________________________________________________It's not that I can't spell: it is that I can't type.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check