Barrels 101

[dewatters]

Those are very interesting articles. I'd like to track down the other articles in the series. Thank you for posting those up.

The other CHF articles can be found here:

http://technology.calumet.purdue.edu/met/higley/

[lre433]

Regarding Rate of Twist,
If I understand correctly, a rate of twist of 1:11 is more efficient for lighter grained bullets, but doesn't do so well with heavy bullets. However, a 1:7 twist is needed for a heavy bullet, but will it be just as effective with a light weight bullet?

[Eric D.]

That is correct. 1/7 is sort of a catch all for heavy bullets in the 70 gr range and above and works with bullets on down to 55 gr. Less than 55 gr though and you're approaching the threshold of over-stabilization

Regarding Rate of Twist,
If I understand correctly, a rate of twist of 1:11 is more efficient for lighter grained bullets, but doesn't do so well with heavy bullets. However, a 1:7 twist is needed for a heavy bullet, but will it be just as effective with a light weight bullet?

[Onyx Z]

That is correct. 1/7 is sort of a catch all for heavy bullets in the 70 gr range and above and works with bullets on down to 55 gr. Less than 55 gr though and you're approaching the threshold of over-stabilization

That's why I prefer 1/8 twist. They can handle the whole spectrum of mag length loads. My precision barrel is 1/8, but it's pretty tough to find a chrome lined 1/8 barrel for some reason.

[markm]

That's why I prefer 1/8 twist. They can handle the whole spectrum of mag length loads. My precision barrel is 1/8, but it's pretty tough to find a chrome lined 1/8 barrel for some reason.

You should be looking at SIONICs, MAMA!! That's their barrel.

[MistWolf]

That is NOT correct. Bullet weight has little to do with the twist needed to stabilize the bullet. It's bullet LENGTH. A short round nosed bullet can weigh as much as a long pointy bullet and need less twist to stabilize. A bullet with a lead core will weigh more than a bullet of the same shape made of solid copper and both will need the same twist

[Onyx Z]

That is NOT correct. Bullet weight has little to do with the twist needed to stabilize the bullet. It's bullet LENGTH. A short round nosed bullet can weigh as much as a long pointy bullet and need less twist to stabilize. A bullet with a lead core will weigh more than a bullet of the same shape made of solid copper and both will need the same twist

And typically, the heavier the bullet, the longer it is... of course there are exceptions to every rule.

Theoretically, a 1/8 can shoot the longer/heavier bullets and the shorter/lighter bullets without the worry of spinning them apart. In the end, both 1/7 and 1/8 will work for what is typically put through an AR.

[jstone]

That is correct. 1/7 is sort of a catch all for heavy bullets in the 70 gr range and above and works with bullets on down to 55 gr. Less than 55 gr though and you're approaching the threshold of over-stabilization

Bullets are either stabil or they are not. You can cause a bullet to break up from to fast of a twist rate in a barrel. But you can not over stabilize a bullet. Over stabilization is an oxy moron.How can something be to stabil.

[lre433]

Ok. Thanks. Is there a chart somewhere that breaks down the rate of twist in relation to the weight/length or surface area of the bullet?

[lre433]

I have been trying to build my knowledge on barrels and until now, thought chrome lined was the best for durability. I have just been reading some posts about Melonite treated/coated barrels. This process seems to be gaining popularity. What can you tell me about Melonite barrels? Thanks...