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1/7-1/12 62g hp? which one

kycaddy24
I picked up a case of silver bear 62g hp .223. I have two uppers for my ar one is a 1/7 and one is a 1/12. I know these are at opposite ends of the whole twist ratio. Both uppers are 20inch. One is a a1 one is a2, not that it really matters. What one would you shoot? no scopes on either one thnks
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5 comments

Date Votes
  • buschmaster
    the faster 1/7 twist is needed to stabilize the heavier 69 gr. bullet.

    the lighter 55 gr bullet put through a 1/7 twist will overstabilize it and almost every shot will be sort of a flier. groups open up to around 4" at 100 yds. I know because I did it and that's what happened. 1/12 is the correct twist for that weight.

    so you have to match up the weight with the twist. you have 69 gr, use the 1/7 barrel.

    1/9 barrels were a compromise so you can acceptably shoot either 55 or 69 gr thorugh the same barrel.
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  • kycaddy24
    thanks, do you know the heaviest bullet you can shoot 1/7 ? I ask this because I seen some 80gr on ammoman.com it said "Do not shoot this unless you have a match throat" is this true
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  • Cubslover
    quote:Originally posted by kycaddy24
    thanks, do you know the heaviest bullet you can shoot 1/7 ? I ask this because I seen some 80gr on ammoman.com it said "Do not shoot this unless you have a match throat" is this true


    You'll need a 1:7 twist with a longer throat to shoot the heavy guys. I've seen 90's avail in .224 for 223 shooting at medium-long ranges.

    That larger bullet is much longer and when chambered in a standard length throad, will entail very high pressures.
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  • youngsparkey
    I was told to watch out for over stabilization with a 55 gr. in a 1/9 and the higher end of hand loads also.
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  • kycaddy24
    One of my uppers is a 1/7 twist how do you know if the throat is long enough
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