Twist Rate on Barrels?

[thearrower]

I normally bow hunt and very seldom pick up a rifle....However, I am coming to this forum with a question that I really would like to understand. Why is the barrel twist rate sometimes so different on similar cartridges? How are these twists determined, what is their primary effect, etc.....Again, I apologize for my lack of knowledge.

[Lungbustr]

The rifling spins the bullet to stabilize it, for accuracy. So when you shoot a longer or heavier bullet you want a higher twist rate to stabilize it properly.

Here is something I grabbed off the net as an example in relation to ar style rifles. http://info.stagarms.com/blog/bid/37...unition-Choice

[thearrower]

The rifling spins the bullet to stabilize it, for accuracy. So when you shoot a longer or heavier bullet you want a higher twist rate to stabilize it properly.

Here is something I grabbed off the net as an example in relation to ar style rifles. http://info.stagarms.com/blog/bid/37...unition-Choice

Thanks for the info.........helps me get some understanding.

[bm22]

I am no expert but a twist rate is how many inches it takes for the lands and groves to make a complet circle. For instance a 1 in 10 twist which is common on .308, the lands make a complet twist every 10'inches of barrel.

To check put brush on a cleaning rod and make a mark on the top of the rod. Slowly pull the rod out until the mark comes back to the top. Measure how many inches of rod you pulled out.

The Faster the twist the heavier bullet the gun will stabilize. The old .223 barrels were 1:12 which will barely stabilze a 55 gr bullet. The common AR twist is 1:9 which will stabilze up to a 65ish grain bullet. 1:7 can shoot the heavies of 77-80 grain but is too fast to stabilze a 50 grain and below bullet.

Depending on what bullet you want to shoot will determine the twist on your rifle.

Hope this helps.

[bboswell]

These guys hit it.


There is a balancing act, faster twist stabilizes bigger bullets but too fast of twist robs FPS.

[thearrower]

I am no expert but a twist rate is how many inches it takes for the lands and groves to make a complet circle. For instance a 1 in 10 twist which is common on .308, the lands make a complet twist every 10'inches of barrel.

To check put brush on a cleaning rod and make a mark on the top of the rod. Slowly pull the rod out until the mark comes back to the top. Measure how many inches of rod you pulled out.

The Faster the twist the heavier bullet the gun will stabilize. The old .223 barrels were 1:12 which will barely stabilze a 55 gr bullet. The common AR twist is 1:9 which will stabilze up to a 65ish grain bullet. 1:7 can shoot the heavies of 77-80 grain but is too fast to stabilze a 50 grain and below bullet.

Depending on what bullet you want to shoot will determine the twist on your rifle.

Hope this helps.

Thanks......so this basicly means that the larger grain bullet I anticipate shooting ....... the higher the rate of twist needs to be....thank you

[thearrower]

These guys hit it.


There is a balancing act, faster twist stabilizes bigger bullets but too fast of twist robs FPS.

Ok, I can see how that would work. I am considering a custom rifle build and I am trying to work backward from the bullet and velocity to get what I think I am after. Like I said................ I am primarily a bow hunter. But, I am thinking I would like a 400 to 500 yard rifle. Just trying to figure it all out.

[bm22]

What caliber are you looking at? What do you want to shoot with it? And how far?

[PYBUCK]

Randall, A 1:9 twist will usually suffice for most bullets used for hunting, even out to 4-5 hundred yards.

[thearrower]

What caliber are you looking at? What do you want to shoot with it? And how far?

Looking for a medium to medium large animal harvest at 400 yards plus. The smallest caliber I am looking at is the 257 Weatherby Mag. or a 264 Winchester Mag.

[thearrower]

Randall, A 1:9 twist will usually suffice for most bullets used for hunting, even out to 4-5 hundred yards.

Thanks Dean,

Knowing you are a huge bowhunter also.........I am probably looking at something close to what you would prefer. It is just that no matter how much I like the stick and string ...... there are times I have had opportunities to hunt with a rifle when either a bow was not practical or not allowed. My wife hunts with both a bow and a rifle..... and she shoots a 257 weatherby. It seems to work well for her. That is probably the smallest I would want to go with.

[treestand]

Optimum twist rate is a function of bullet diameter and length. 45 caliber rifles usually have a 1:20 twist rate. 30 caliber is usually 1:10. As mentioned above, the 223 rate is 1:9 for standard 55 grain bullets but faster for longer bullets such the 69 grain.

[thearrower]

Thanks......appreciate the explanation and input

[savin yours]

Thanks, I learned something too.

[bm22]

Since you are a bowhunter first I would go with the tried and true .308.

You have the best factory ammo available. 1:10 twist.