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55 versus 62 grain bullet drop

bingeebobbingeebob Member Posts: 1,185 ✭✭✭✭✭
edited July 2004 in Ask the Experts
I am preparing for USMC recruit training with the help of a 20+ years Marine Gunny, i am using a bushmaster 20''. we are using 55grain bullets for now, but we are only firing at 200 yards, when we move up to 300, and then 500, will the 55 grain bullets drop more than the 62 grain rounds i will use in recruit training? and how should i adjust for this drop, if it is even present, or should i just get some real NATO SS109 rounds??
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    Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    You need to know the MV (actual for each weight, out of your rifle) and the BC of both bullets. After that you simply plug the numbers into one of the online ballistic calculaters.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
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    TED GARTED GAR Member Posts: 389 ✭✭✭
    edited November -1
    When you start changing bullet weights you have to take into consideration the twist rate. The 1/12 twist is good for 45-55 grain.
    It will barely stabilize the 62 grain. The 1/7 twist is designed for the 62 grain SS109, IF you have the 1/9 twist you can shoot 45-69 grain, with great accuracy. IF you have the 1/8 twist you will be better off with the 70-79 grain projectiles..
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    bingeebobbingeebob Member Posts: 1,185 ✭✭✭✭✭
    edited November -1
    it is a 1/9 twist. I want to use the same system that gunny is teaching me with the windage and elevation adjustments, so i dont need to worry about the difference in weight?
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    It seems to me that you have your answer in your first post. Train and practice with the ammunition that you will be working with when you go through your official training. Get some SS109 and use it for your practice. I saw that Midway has some on sale but you can usually beat their prices with some of the bulk ammunition suppliers.

    Best.

    And your 1:9 twist will be just fine for the SS109 62 gr. bullets.
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    TED GARTED GAR Member Posts: 389 ✭✭✭
    edited November -1
    10-4 I love the 1/9 twist. It has been adopted by the majority of
    shooters clubs, and military as well, The HBAR is a 1/9 twist. and is a favorite, Because of the way it stabilizes, the different grain bullets.
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