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Barrel Twist

SuburbanNoize
PLanning on a range trip today, need to pick some ammo up, The barrel twist on my M4 is 1/9, can i used 55 grain in there and be accurate? All i cna find is 55 grain around here, ive got on box of 75 grain tap ammo as well. Thanks guys.
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Comments

6 comments

Date Votes
  • dbain99
    55 grain in a 1 in 9 twist is the standard. For long shots (300+) with heavier bullets a faster twist is recomended.
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  • Horse Plains Drifter
    You should be fine I think.
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  • rustyh
    Gentlemen: Why would a heavier bullet be preferred with a faster twist barrel? I would think that a faster twist barrel would not have enough time to influence a heavier bullet. That is get it rotating any faster than a lighter bullet. Inertia and all. Just wondering about the physics.
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  • dbain99
    The twist rate 1/7 means 1 twist every 7 inches traveling down the barrel. Time doesnt have anything to do with it per say. Immedately upon leaving the muzzel the bullet twist begins to decelerate, so if you intend to stabalize a heavier bullet at a longer range a higher rate of twist is desired.
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  • SuburbanNoize
    This is a 16 in barrel if it matters!
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  • mrbruce
    The print on a box of 75 grain A-max bullets state that a 9 twist is needed.....
    Light weight bullets can also be used in the same twist, but anything above 75 grains
    probably wont stabilize in a 9 twist.....
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