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Thread: Big bore Auto

  1. #1
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    Talking Big bore Auto

    Murphy......
    Some time back, someone built a Browning BAR in 458 Winchester Magnum. Was there an artical printed about it or any loading information printed in any article's. Would like the loading info and the gunsmith that did the conversion. Thanks

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    I'm not aware of BAR conversions but there is a conversion offered to convert an M1 Garand to either .338 mag or .458 mag. see: http://www.gokart.net/shop-utopia/mc...458garand.html

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    Oh my God! CrustyJohn why did you have to post that link? Now I've seen something that has pushed it's way to the top of my "Must Have" list. An M1 Garand in .458 Win Mag..........ah, the kids don't need to go to college.

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    I don't know about a 458 mag in a BAR or a Garand, but the interest in converting a Garand to fire something bigger came on here some time back and I do know of one that was converted to 338-06 and it works fine. The task is complicated with the gas system, we must maintain about 14,500 psi at the port or change the port diameter to give the same thrust energy to the actuating rod. In the case with the 338 a 30 caliber barrel was rebored and rifled to 338 and I think the port was left the same. By my calculations with the same powders (RL-15, IMR 4064, 4895, etc) the gas pressure at the port would be less by about 20% from the 30-06 but it does work. This would allow the use of heavier bullets (250 grains) and slower powder (RL-19 and 4831).

    The 458 uses faster powder but has a much higher expansion ration so it may work without changing the port size.

    The BAR uses a tappet gas system and can handle a much broader range of gas pressures and is currently made in the 338, 300, 7mm mag and would likely work fine with a 458 barrel.
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    That is very kewl.
    Great spirits have always found violent opposition from mediocre minds. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence. Albert Einstein

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    Their is a company that is making the 450 Marlin in a AR 15 style rifle. They call it "The Thumper".

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