Barrel Question

[ltorlo64]

I am trying to decide between two rifle kits, one has a 1 in 7 twist, the other has a 1 in 9 twist. The price of each is about equal. From what I have been reading, the 1 in 7 is better for accuracy. Will it make that much difference or am I looking at this wrong?

[Gunreference1]

ltorlo64, you will want to pay attention to bullet weight when it come to barrel twist. Heavier bullets require a 'faster' rate of twist. In the .223/5.56 world the 1 in 9" twist rate is the happy medium for most people. If you're sticking with bullets less than about 73 grs. then a 1 in 9" twist rate would work. It you plan on using heavier bullets then you would want someting with a 1 in 7" twist rate. Hope this helps!

Steve

[ltorlo64]

ltorlo64, you will want to pay attention to bullet weight when it come to barrel twist. Heavier bullets require a 'faster' rate of twist. In the .223/5.56 world the 1 in 9" twist rate is the happy medium for most people. If you're sticking with bullets less than about 73 grs. then a 1 in 9" twist rate would work. It you plan on using heavier bullets then you would want someting with a 1 in 7" twist rate. Hope this helps!

Steve

Actually, that is very helpful. I would expect to stay between 50-63 grs, so the 1 in 9 should be fine. Thanks for the help.

[slamfire51]

All the ARs I've owned were 1 in 9 and I was very satisfied using 55 gr. bullets.
I don't thing you'll go wrong with the 1 in 7.

[Dafapa]

I think with a 1:7 barrel you might actually have some issues using the very common 55 gr stuff available.

[shadow65]

55gr. should do fine in a 1/7. 50 gr. is getting kind of low for a 1/7.
Military has used 1/7 for a while and were using XM193 which is 55 gr.

[ltorlo64]

So, what is the problem if the twist rate is too high?

[swampdragon]

So, what is the problem if the twist rate is too high?

The bullet gets dizzy.

[slamfire51]

Also if the velocity is extremely high, and a thin bullet jacket is used (some varmint bullets) the jacket will sometimes separate from the core.

[swampdragon]

Faster twists also burn out barrels faster too.

[ready]

To further complicate matters, alot of precision barrels are 1:8.

[aliceinchains]

To further complicate matters, alot of precision barrels are 1:8.



Now you done made it complicated.:bigsmilebounce:

[ltorlo64]

The bullet gets dizzy.

I should have figured that out myself!

[ltorlo64]

To further complicate matters, alot of precision barrels are 1:8.

:dizzy:

[Schuetzenman]

So, what is the problem if the twist rate is too high?

A cheap 55 gr. bullet can sometimes throw off it's jacket around 150 yards down range from a 1 in 7. Seen it done several times, but they were handloads the shooter had made up.

I know most get 1 in 9 twist and I have one myself. Still for the greatest flexibility in what you could shoot in the weapon the 1 in 7 would be better IMHO. On burning out an AR15 barrel, normal competitive life span for a Service Rifle competition gun is 10,000 rounds. At the current costs of .223 ammo even if reloading I doubt you'll be buring anthing out in your lifetime.

Oh and on the 1 in 8 that is the most common twist for match rifles. I have an 8 twist Kreiger SS barrel and it is very accurate. The 8's are used for Sierra Match King 80 gr. BTHP bullets. That bullet is as long as a 147 gr. Nato spec 7.62 bullet. Looks like an over grown sewing needle.

[swampdragon]

I should have figured that out myself!

S'man is right about the barrel burn out thing.
It is true the faster twist will burn out sooner, but it really does depend on rounds fired.