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Old October 9, 2018, 02:34 PM   #1
rebs
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Barrel of choice ?

I have two AR 15's one with a 9 twist 20" barrel and one with an 8 twist 16" barrel. For shooting 69 gr SMK's at 300 yds which would be the better choice barrel ?
I made a mistake with the 12 twist its a 9 twist 20"

Last edited by rebs; October 9, 2018 at 08:45 PM.
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Old October 9, 2018, 06:08 PM   #2
imashooter
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1:8
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Old October 9, 2018, 06:22 PM   #3
stagpanther
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Uhhh, try em both and see?
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Old October 9, 2018, 06:50 PM   #4
jmr40
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I'd take the 8 twist every time. Especially with those bullet weights. The 12 twist will be OK with bullets 55 gr and lighter. But an 8 twist should be very versatile and work with all but the heaviest bullets.
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Old October 9, 2018, 07:27 PM   #5
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A 1 in 12 is best for 55gr and under, you might manage to do well with 62gr bullets in a 20in if the velocity is good enough.

A 1 in 9 is good for up to 69gr in a 20in barrel and maybe even in a 16in... And 1 in 7 can handle up to around 80gr well from a 16in barrel.

1 in 8 can do up around 75gr in a 16in barrel.


Your results may vary, as these are just rough guidelines.
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Old October 9, 2018, 08:46 PM   #6
rebs
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Thank you guys for the replies
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Old October 10, 2018, 06:11 AM   #7
Mobuck
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I've done OK with a 1-9 20" shooting 60-69 grain bullets. Under 20" not as good. Using that heavy bullet in a marginal twist demands the higher velocity that the 20" produces.
A 69 grain from a 16" barrel is going to get pretty "droopy" at 300 yards.
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Old October 11, 2018, 02:32 PM   #8
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1n8 twist.

Dedicate that 1n9 to a 55gr and under varmint barrel.
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Old October 11, 2018, 08:28 PM   #9
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Thank you for the replies I appreciate it.
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