1:7 or 1:9 twist

[Bad Dog]

OK...What are the advantages of one over the other?

[esaabye]

OK...What are the advantages of one over the other?

Depends on the bullet weight you want to shoot. 1/9 max generally is considered 69gr, 1/8 or 1/7 can do the 77 and 80gr bullets. Only people who shoot those that I know of are high power shooters at 600 and 1000 yds. My new highpower upper is a 1/7.5 and I will shoot 69gr to 300yds and 77grs at 600.

[Bad Dog]

I got it, but I have a barrel with a 1:7 twist do I have to shoot heavier bullets or can I stick with the 55 grain bullets I have been shooting? Will this affect my accuracy if I'm shooting 300 yrds max?

[hurley842002]

I got it, but I have a barrel with a 1:7 twist do I have to shoot heavier bullets or can I stick with the 55 grain bullets I have been shooting? Will this affect my accuracy if I'm shooting 300 yrds max?

You can shoot 55 grains just fine

[Hoopty]

What about the heavier bullets in 1/9?

[esaabye]

What about the heavier bullets in 1/9?

As I understand it you need the higher twist rate for the 70+ to stabilize the round. Less stable = big group. Not sure if damage can be done to the barrell but Sierra actually puts a warning on the heavys, "For use in 1/7 and 1/8 only.

[hurley842002]

What about the heavier bullets in 1/9?

You can shoot the heavier bullets in a 1/9 barrel, but rather or not a particular 1/9 barrel will stabilize them is a hit or miss. Some 1/9 barrels will stabilize heavier bullets no problem, some will not. As far as damage, you won't do any damage to the barrel by shooting the heavier bullets. I had a 1/9 Bushmaster upper that shot 75gr Hornady's no problem, but i've since gone with a 1/7 BCM for a few different reasons.

[gcrookston]

You can shoot 55 grains just fine

+1.

Generally speaking, the 1:9 is optimal for 55 gr., the 1:7 for the 62 gr. but both barrel twist rates should present them selves well with a spectrum of bullet weights. The tighter the twist, the heavier the bullet.