Barrel of choice ?

rebs · October 9, 2018, 02:34 PM

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"

imashooter · October 9, 2018, 06:08 PM

1:8

stagpanther · October 9, 2018, 06:22 PM

Uhhh, try em both and see?

jmr40 · October 9, 2018, 06:50 PM

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.

marine6680 · October 9, 2018, 07:27 PM

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.

rebs · October 9, 2018, 08:46 PM

Thank you guys for the replies

Mobuck · October 10, 2018, 06:11 AM

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.

bfoosh006 · October 11, 2018, 02:32 PM

1n8 twist.

Dedicate that 1n9 to a 55gr and under varmint barrel.

rebs · October 11, 2018, 08:28 PM

Thank you for the replies I appreciate it.

October 9, 2018, 02:34 PM	#1
rebs Senior Member Join Date: January 10, 2012 Posts: 3,881	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.

October 9, 2018, 06:22 PM	#3
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,789	Uhhh, try em both and see? __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

October 9, 2018, 06:50 PM	#4
jmr40 Senior Member Join Date: June 15, 2008 Location: Georgia Posts: 10,809	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. __________________ "If you're still doing things the same way you were doing them 10 years ago, you're doing it wrong" Winston Churchill

October 9, 2018, 06:08 PM	#2
imashooter Senior Member Join Date: December 28, 2013 Location: Alabama Posts: 395	1:8

October 9, 2018, 07:27 PM	#5
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	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.

October 9, 2018, 08:46 PM	#6
rebs Senior Member Join Date: January 10, 2012 Posts: 3,881	Thank you guys for the replies

October 10, 2018, 06:11 AM	#7
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	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.

October 11, 2018, 02:32 PM	#8
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	1n8 twist. Dedicate that 1n9 to a 55gr and under varmint barrel.

October 11, 2018, 08:28 PM	#9
rebs Senior Member Join Date: January 10, 2012 Posts: 3,881	Thank you for the replies I appreciate it.