Rifle barrels are designed to incorporate lands and grooves that spin the projectiles they fire so that they will fly true and hit point-on. That is the fundamental definition of a rifle, it uses a rifled barrel. Rifle barrels are grooved so that the bullet makes one complete turn in a given number of inches on its trip down the barrel.

There seems to be an inordinate interest in twist rates these days. With very few exceptions the major manufacturers have carefully and correctly researched the subject and experimented to determine the most appropriate twist rate for each caliber. There is very little to be gained by second guessing their conclusion.

For those who cannot leave well enough alone, here is a formula for calculating twist rate:

What follows is a list of the rates of twist for common rifle cartridges. These were taken from various sources. The rates of twist below are expressed as "one complete turn in so many inches" (i.e. 1 in 9", 1 in 10", etc.).

.17 HMR = 1 in 9"
.22 Long Rifle = 1 in 16"
.222 Remington = 1 in 14"
.223 Remington = 1 in 12"
.22-250 Remington = 1 in 14"
.223 WSSM = 1 in 12"
.243 Winchester = 1 in 10"
6mm Remington = 1 in 9"
.243 WSSM = 1 in 10"
.240 Wby. Mag. = 1 in 10"
.25-06 Remington = 1 in 10"
.257 Wby. Mag. = 1 in 10"
6.5x55 Swedish Mauser = 1 in 8"
.260 Remington = 1 in 9"
.264 Win. Mag. = 1 in 9"
.270 Winchester = 1 in 10"
.270 WSM = 1 in 10"
.270 Wby. Mag. = 1 in 10"
7x57 Mauser = 1 in 9"
7mm-08 Remington = 1 in 9.25"
.280 Remington = 1 in 9.25"
7mm Rem. SAUM = 1 in 9.25"
7mm WSM = 1 in 9.5"
7mm Rem. Mag. = 1 in 9.25"
7mm Wby. Mag. = 1 in 10"
.30 Carbine = 1 in 16"
.30-30 Winchester = 1 in 12"
.300 Savage = 1 in 10"
.308 Winchester = 1 in 12"
.30-06 Springfield = 1 in 10"
.300 Rem. SAUM = 1 in 10"
.300 WSM = 1 in 10"
.300 Win. Mag. = 1 in 10"
.300 Wby. Mag. = 1 in 10"
7.62x39 Soviet = 1 in 7.5"
.303 British = 1 in 10"
.32 Win. Spec. = 1 in 16"
8x57 JS Mauser = 1 in 9.25"
.338-57 O'Connor = 1 in 10"
.338 Win. Mag. = 1 in 10"
.340 Wby. Mag. = 1 in 10"
.357 Mag. = 1 in 16"
.35 Remington = 1 in 16"
.35 Whelen = 1 in 16"
.350 Rem. Mag. = 1 in 16"
.375 H&H Mag. = 1 in 12"
.378 Wby. Mag. = 1 in 12"
.416 Rem. Mag. = 1 in 14"
.416 Wby. Mag. = 1 in 14"
.44 Rem. Mag. = 1 in 20"
.444 Marlin = 1 in 20"
.45-70 Govt. (Marlin and Ruger rifles) = 1 in 20"
.450 Marlin = 1 in 20"
.458 Win. Mag. = 1 in 14"
.460 Wby. Mag. = 1 in 16"

NOTE: For a more comprehensive list that covers many more calibers see the Expanded Rifle Barrel Twist List.