Gunsmithing Calibers and Twists Rates

[popeyecop]

Ran Across this chart at Brownells


This chart outlines the basic principles

Caliber Twist

.172 10" For all bullets

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

.224 CF 9" For bullets heavier than 63 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
10" For bullets up to 120 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 105 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 120 gr.
9" For bullets up to 120 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 220 gr.
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

.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

.451 16" For all bullets

.458 14" For all bullets
*Stainless Steel only

 

[Goatman007]

Re: Calibers and Twists Rates

There is a formula on the internet somewhere, Type in rifle barrel twist rates, saw the formula in "Rifle" magazine somewhere years ago.

 

[mike_l]

Re: Calibers and Twists Rates

Search for greenhill formula