Rate-of-Twist vs. Bullet Weight

idsman75

Okay, I know muzzleloaders tend to have a guideline with regards to bullet weight vs. rate of twist (or so I've heard). Traditional muzzleloaders with slow rates of twist seem to like patched balls while the modern muzzleloaders with faster rates of twist seem to like saboted heavier bullets. At least that's according to my limited experience and what I've read.

Let's talk modern rifles for a moment. I don't handload but I'm really leaning towards that direction. I have a new Remington 700 XCR in .30-06 with a 1:10 rate-of-twist and a 24" barrel. I've never thought of it though I know the M-16 series of rifles tend to have faster rates-of-twist available for people who want to use the heavier bullets. Is this something that is more of a concern for precision rifles with barrels made to precise tolerances to maximize accuracy or does this apply to simply great or good rifles as well. In other words, is there a range of bullet weights on which I should focus for my Remington when I start handloading or is it a shot in the dark what my gun will like to digest?

The Butcher

1-10 twist will be good for bullets larger than 168 grains. According to my twist rate chart, your rifle should shoot 200-220gr bullest the best. Others I'm sure have some input.

Hawk Carse

The .30-06 with 10" twist will handle bullet weights from 110 to 250 grains. (Length matters, not weight, that 250 should be a roundnose.) Which it handles the most accurately depends largely on the individual rifle. One of mine does extremely well with 130 gr Speers, the other with 175 gr Sierras. The latter will be tried with 190s the next time I load '06.

Rifling twist in sporting rifles is generally overstudied these days. The Army and the match shooters have done a lot of work on it that only applies in specific applications. Want a 14" twist .30 caliber barrel? A score benchrest shooter loading 133 grain flatbase bullets does. An 8" twist .30? Needed for a Whisper shooting 240s subsonic.

If for target shooting, I'd start that Remington with some 175 gr Sierra Match Kings and work outwards from there. That is what I have been shooting in a 10" twist .308.

mrbruce

A 165 grain bullet has always been the go to hunting bullet for a 30-06, and that is where I would start looking.

idsman75

Are there any good publications that match appropriate bullet weights with rates-of-twist and the concept of "round nose" vs "pointed nose"?

nononsense

idsman75,

there might be somewhere but it will take some looking. Here is the breakdown from Sierra Bullets:

.308

8" For bullets heavier than 220gr.
10" For bullets up to 220 gr.
12" For bullets up to 170 gr.
14"* For bullets up to 168 gr.
15"* For bullets up to 150 gr.

Roundnose vs. spitzer is still the problem of length as opposed to weight or form factor. It's just that normally the roundnose bullets are shorter by comparison to spitzers with the same weight:



Best.

Added:

Here is a fairly simple twist rate calculator:

http://kwk.us/twist.html

Best.

B17-P51

It has been said here and plenty of other places that overstabilizing a light bullet will have no bad effects ( other than an extremely light bullet possibly coming apart),however understabilizing will have negative effects on accuracy on heavy bullets. That said; a 1/10 twist in a .308 cal rifle should shoot all bullets.(100 to 180 gr) well. But a 1/12 should not shoot extemely heavy bullets well (190 to 250 gr). This is exactly as it is in the real world so I would be inclined to believe this info.

idsman75

quote:Originally posted by nononsense
idsman75,

there might be somewhere but it will take some looking. Here is the breakdown from Sierra Bullets:

.308

8" For bullets heavier than 220gr.
10" For bullets up to 220 gr.
12" For bullets up to 170 gr.
14"* For bullets up to 168 gr.
15"* For bullets up to 150 gr.

Roundnose vs. spitzer is still the problem of length as opposed to weight or form factor. It's just that normally the roundnose bullets are shorter by comparison to spitzers with the same weight:



Best.

Added:

Here is a fairly simple twist rate calculator:

http://kwk.us/twist.html

Best.





Would this be something I could find in the Sierra handloading manual? I appreciate all the input on this.

nononsense

idsman75,

Here is the full list:

Recommended Twist Rate - Courtesy of Shilen
The information below will help you select the best barrel twist for your specific needs, providing of course there are multiple choices. If you'll be shooting one bullet weight, choose a twist from the chart just fast enough to stabilize it. Too fast a twist simply overspins the bullet and may result in reduced accuracy. On the other hand, a twist too slow for any bullet will likely produce instability, keyholing and rotten accuracy. So if you're going to be using several bullet weights, be sure to select a twist that will stabilize the heaviest one, since lighter bullets will also be stabilized.
By way of explanation, the numbers in the "Twist" column indicate how far the bullet must travel through the bore to make one full revolution. This is determined by the rate of rotation of the rifling. For example, a 9"-twist barrel spins the bullet one full turn when it passes 9 inches through the bore. In a 16"-twist barrel, the bullet makes one revolution in 16 inches. So at the same bullet velocity, the 9" twist is faster (spins the bullet faster) than the 16" twist. Consequently, as the chart reflects in the .224 CF section, the 9" twist is necessary for stabilizing heavier bullet weights.
Again looking at the .224 CF section, if you're planning to shoot 55-grain bullets, the 14" twist is ideal. This twist is also the best choice for 52- and 53-grain match bullets driven at moderate velocities. But if you're also contemplating shooting a 60-grainer, go with the 12" twist, since it will stabilize all the bullets you'll be using. As you can see from the 15" and 16" twists, higher velocities also spin the bullet faster and may enable a slower-than-recommended twist to stabilize a marginally overweight bullet. However, this is tricky stuff best left to those who are highly experienced in operating at the ragged edge of stability and sanity.
The basic principles just outlined apply to all the calibers below. But, if you have questions or need a recommendation, let us know.

Caliber Twist

.172 9" For bullets heavier than 30 gr.
10" For bullets up to 30 gr.

.204/20 12" For all bullets.

.222 RF 14"* Twist for pistol barrels
16" Standard twist for rifle barrels
17"* Special twist for rifle barrels

.224 CF 8" For bullets heavier than 70 gr.
9" For bullets up to 70 gr.
12" For bullets up to 63 gr.
14" For bullets up to 55 gr.
15"* For bullets up to 55 gr. driven 4,100 fps or more
16"* For bullets up to 55 gr. driven 4,300 fps or more

6mm/.243 8" Special for VLD bullets over 100 gr.
10" For bullets up to 120 gr. and VLD under 100 gr.
12" For bullets up to 85 gr.
13"* For bullets up to 75 gr.
14"* For bullets up to 70 gr.
15"* Special for bullets up to 70 gr.

.257 9" For bullets heavier than 100 gr.
10" For bullets up to 100 gr.
12" For bullets up to 90 gr.
13"* For bullets up to 80 gr.
14"* For bullets up to 70 gr.

6.5mm/.264 8" For bullets heavier than 130 gr.
9" For bullets up to 130 gr.

.270 10" For all bullets

7mm/.284 9" For bullets heavier than 140 gr.
11" For bullets up to 140 gr.

.307 13"* Special size and twist

.308 8" For bullets heavier than 220gr.
10" For bullets up to 220 gr.
12" For bullets up to 170 gr.
14"* For bullets up to 168 gr.
15"* For bullets up to 150 gr.

7.65mm/.311 10" For all bullets

8mm/.323 10" For all bullets

.338 10" For all bullets

9mm/.355 14" For low-velocity wadcutters
16" For all other bullets

.38/.357 14" For low-velocity wadcutters
18" For all other bullets

.358 14" For all bullets

.375 12" For all bullets

10mm/.400 16" For all bullets

.411 14" For all bullets

.416 14" For all bullets

.44 20" For all bullets
16" For low velocity wadcutters

.451 16" For all bullets

.458 14" For all bullets

*Stainless steel only
Black powder barrels (1.250" x 30")
.32 14" .320" groove
.38 20" .379" groove
.40 20" .403" groove
.457 20", 14" .457" groove

Best.

idsman75

quote:Originally posted by nononsense
idsman75,

Here is the full list:

Recommended Twist Rate - Courtesy of Shilen
The information below will help you select the best barrel twist for your specific needs, providing of course there are multiple choices. If you'll be shooting one bullet weight, choose a twist from the chart just fast enough to stabilize it. Too fast a twist simply overspins the bullet and may result in reduced accuracy. On the other hand, a twist too slow for any bullet will likely produce instability, keyholing and rotten accuracy. So if you're going to be using several bullet weights, be sure to select a twist that will stabilize the heaviest one, since lighter bullets will also be stabilized.
By way of explanation, the numbers in the "Twist" column indicate how far the bullet must travel through the bore to make one full revolution. This is determined by the rate of rotation of the rifling. For example, a 9"-twist barrel spins the bullet one full turn when it passes 9 inches through the bore. In a 16"-twist barrel, the bullet makes one revolution in 16 inches. So at the same bullet velocity, the 9" twist is faster (spins the bullet faster) than the 16" twist. Consequently, as the chart reflects in the .224 CF section, the 9" twist is necessary for stabilizing heavier bullet weights.
Again looking at the .224 CF section, if you're planning to shoot 55-grain bullets, the 14" twist is ideal. This twist is also the best choice for 52- and 53-grain match bullets driven at moderate velocities. But if you're also contemplating shooting a 60-grainer, go with the 12" twist, since it will stabilize all the bullets you'll be using. As you can see from the 15" and 16" twists, higher velocities also spin the bullet faster and may enable a slower-than-recommended twist to stabilize a marginally overweight bullet. However, this is tricky stuff best left to those who are highly experienced in operating at the ragged edge of stability and sanity.
The basic principles just outlined apply to all the calibers below. But, if you have questions or need a recommendation, let us know.

Caliber Twist

.172 9" For bullets heavier than 30 gr.
10" For bullets up to 30 gr.

.204/20 12" For all bullets.

.222 RF 14"* Twist for pistol barrels
16" Standard twist for rifle barrels
17"* Special twist for rifle barrels

.224 CF 8" For bullets heavier than 70 gr.
9" For bullets up to 70 gr.
12" For bullets up to 63 gr.
14" For bullets up to 55 gr.
15"* For bullets up to 55 gr. driven 4,100 fps or more
16"* For bullets up to 55 gr. driven 4,300 fps or more

6mm/.243 8" Special for VLD bullets over 100 gr.
10" For bullets up to 120 gr. and VLD under 100 gr.
12" For bullets up to 85 gr.
13"* For bullets up to 75 gr.
14"* For bullets up to 70 gr.
15"* Special for bullets up to 70 gr.

.257 9" For bullets heavier than 100 gr.
10" For bullets up to 100 gr.
12" For bullets up to 90 gr.
13"* For bullets up to 80 gr.
14"* For bullets up to 70 gr.

6.5mm/.264 8" For bullets heavier than 130 gr.
9" For bullets up to 130 gr.

.270 10" For all bullets

7mm/.284 9" For bullets heavier than 140 gr.
11" For bullets up to 140 gr.

.307 13"* Special size and twist

.308 8" For bullets heavier than 220gr.
10" For bullets up to 220 gr.
12" For bullets up to 170 gr.
14"* For bullets up to 168 gr.
15"* For bullets up to 150 gr.

7.65mm/.311 10" For all bullets

8mm/.323 10" For all bullets

.338 10" For all bullets

9mm/.355 14" For low-velocity wadcutters
16" For all other bullets

.38/.357 14" For low-velocity wadcutters
18" For all other bullets

.358 14" For all bullets

.375 12" For all bullets

10mm/.400 16" For all bullets

.411 14" For all bullets

.416 14" For all bullets

.44 20" For all bullets
16" For low velocity wadcutters

.451 16" For all bullets

.458 14" For all bullets

*Stainless steel only
Black powder barrels (1.250" x 30")
.32 14" .320" groove
.38 20" .379" groove
.40 20" .403" groove
.457 20", 14" .457" groove

Best.





Wow! Everyone collectively answered all my questions! Thank you ATE Crew!