1/9 vs 1/7 twist whats the advantage in 223

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grizzly416

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im going to be ordering a xcr soon and was thinking about ordering a 6.8spc and getting a 1/7 223 barrel to come with it . for the most part it will be running around in 223 trim. if 1/9 stops stabilizing at 75gr roughly is there a need for 1/7. really if hunting any thing heavier wont have enough speed to open up relliably.so whats the need for 1/7. i think that 1/9 would take care of my needs without having to buy a different barrel . and hoping they make a 6.5 grendel kit for the xcr
 
From what I am told from a few different sources, 55gr .223 is best with a 1/9 twist as compared to 1/7 twist shooting 62gr
Don't take this as gospel, I'd like to know more about your question aswell.
cheers
 
I don't feel there is a need for 1:7 in a semi auto. I prefer 1:8 as a better more versatile twist rate.
Most people run 55gr or 62gr which will be fine in a 1:9.
You can't overstabilize a bullet but you can spin it faster than it is designed for and have it come apart in the air so a 1:7 may limit you from using light weight thin jacketed varmint bullets.
If you were buying a bolt action for long range target shooting a 1:7 would be ideal. The XCR is not known for target shooting accuracy so I wouldn't worry about getting the barrel for heavy target bullets.

Maybe look for the light weight .223 barrel that is available. My buddy had one for his XCR and it made the rifle much less muzzle heavy.
 
I normally shoot 55gr, but when I want to shoot my 77gr Black Hills it's nice that I have the ability to with a 1/7 twist. I never shoot anything lighter than 55gr, so there is no risk of over-spinning. I agree that 1/9 is fine, but I like options.
 
If you want to shoot service or other longer range competition the 1:7 is good for the 69 and 77 grain bullets. If you don't plan on shooting longer range comp then the slower twist is fine.
 
Also, you won't really know how well the specific rifle/barrel will do with a specific load until you try it. I've had good results with 68gr S&B match ammo and the 1 in 10 twist barrel of a Swiss Arms, but this is pushing it for a twist rate that slow.
 
1/7" is better because it will shoot everything. The myth that fast twists won't shoot light bullets in just that, a myth.

My LMT 14.5" 1/7" twist shot tiny bug holes with 52 gr SMKs and H335.

1/9" is a fine twist rate. Nothing wrong with it, but if you come across some heavier bullets (80 gr) you won't be able to shoot them without key-holing.
 
I have a 1/7 on my AR, I do alot of reloading so I shoot 75gr bullets which most say is to heavy for 1/9. If your not going to go heavier then 55gr then there is really no point in going for a faster twist then 1/9.
 
Ar180shooter said:
Also, you won't really know how well the specific rifle/barrel will do with a specific load until you try it. I've had good results with 68gr S&B match ammo and the 1 in 10 twist barrel of a Swiss Arms, but this is pushing it for a twist rate that slow.
Click to expand...

Lots of stuff shoots well at 100m and may well do fine even out to 200m or so, but when you start shooting past 300m paring bullet length with required twist really matters.
Try shooting that 68 gr. stuff at 500m in a 10 twist and tell us how it does.
 
beltfed said:
Lots of stuff shoots well at 100m and may well do fine even out to 200m or so, but when you start shooting past 300m paring bullet length with required twist really matters.
Try shooting that 68 gr. stuff at 500m in a 10 twist and tell us how it does.
Click to expand...

I shoot 77gr bullet with a 1in 9 twist and it was accurate and stable at 500m with a 24" barrel r700. Bullet velocity when in the barrel has more to do with stability then the actual twist rate. The higher the velocity the higher the RPM regardless of twist rate so in a carbine 1in9 or 1in10 might not be enough to stalalize the longer bullets but in a longer barrel it will be because the bullet goes faster.
 
That is true, to some extent you can make up for lack of twist by increasing the velocity to achieve the rpm. I've done this to get 69gr SMKs to work with a 1:10 swissarms but I didn't like the high chamber pressure that I ended up with with that load. The 1:7 twist just makes it easier with heavy bullets.
 
Caleb314 said:
....with a 24" barrel r700.
Click to expand...

HeadDamage's covered it. I'll only add it is a bit easier to push hotter loads and gain velocity in a bolt gun than in an auto loader.
Also, some barrel twists that are marked 1:8, 1:9 or whatever might in actual fact be a fraction thereof...ie. a 1:9 actually being an 8.5 twist.
 
Keep in mind that a marginal load might work during summer but get some frost on the ground and watch it fall apart.

My 8.5/1 rifle has shown it will stabilize 77gr SMKs but I know it will always work with 69gr bullets so that is what I use.
 
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