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Thread: New mold for 7.62x51 in an M1a

  1. #1
    Boolit Bub
    Join Date
    May 2014
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    New mold for 7.62x51 in an M1a

    Hi there...
    I recently acquired an NOE 311-199-SP-K5 4 cavity 2GC 2PB mold.

    This will be used in an M1a for practice shooting and possibly an M1903 Springfield.

    I'm concerned that I can't find much data for 7.62x51 for a heavier bullet like that. The '03..no problem.

    Does anyone have suggestions where to start?

    Thanks

  2. #2
    In Remembrance



    curator's Avatar
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    Using the GC boolit in the M1A, start at about 32 grains of IMR4895 or 4064 and increase at one grain intervals until you get good function and accuracy. Lots of info on cast in the M1A on this sitr if yu do a search.

  3. #3
    Boolit Master
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    Check the Bruce B sticky at the top of the section. He did a lot of testing and reported some great info.
    jim

  4. #4
    Boolit Grand Master


    Larry Gibson's Avatar
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    Definitely read BruceB's sticky. I suggest you start at 24 gr 4895 and use a Dacron filler. Work up in 1 gr increments with at least 5 shot groups but preferably 10 shot groups to loss of accuracy (when the groups begin to go south). With a 10, 11 or 12" twist barrel accuracy will go south before pressure becomes a problem. A load from 28 gr up through around 32 gr (depends mostly on twist) will probably be where accuracy goes south.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  5. #5
    Boolit Bub
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    Quote Originally Posted by Larry Gibson View Post
    Definitely read BruceB's sticky. I suggest you start at 24 gr 4895 and use a Dacron filler. Work up in 1 gr increments with at least 5 shot groups but preferably 10 shot groups to loss of accuracy (when the groups begin to go south). With a 10, 11 or 12" twist barrel accuracy will go south before pressure becomes a problem. A load from 28 gr up through around 32 gr (depends mostly on twist) will probably be where accuracy goes south.
    Yes, the BruceB thread has outstanding information and I have downloaded the table.

    My concern, other than what I voiced with the bullet weight, is the filler. I recall the NRA mag advised against using dacron wad fillers in bottle necked cases as they would case "chamber ringing." This is probably the most expensive rifle I own, and heaven help me if something goes wrong.

    When the weather improves I shall be casting again and we'll see how well this goes.

    Thank you

  6. #6
    Boolit Grand Master


    Larry Gibson's Avatar
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    When it comes to wads and fillers there are wads and there are fillers. There are no "wad fillers". There is one or the other, especially with Dacron.

    Suggest reading post #2 in http://castboolits.gunloads.com/show...use-of-fillers

    The reported misuse of Dacron almost invariably involves the use of a too fast burning a powder and using the Dacron as a wad. I do not recommend either. Reduced loads (less than 80% load density) with 4895 is a proper powder to use in the .308W with a Dacron filler.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  7. #7
    Boolit Bub
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    When you gentlemen speak of 4895, is that H4895 or IMR-4895. I believe they are not the same.

    Thx

  8. #8
    Boolit Grand Master


    Larry Gibson's Avatar
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    They are close enough, especially with a start load given to work up from.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

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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