Q: I know that .22 centrefire rifles, and the .223 in particular, have different rates of rifling twist. These seem to run from 1:14 on the slow side to 1:7 on the fast side. Just what weight of bullets are the different twist rates best suited for?
A: The 1:14 twist is adequate for use with the various thin- jacketed, super explosive projectiles if the muzzle velocity is held below 3300fps. The standard 1:12 twist of the .223 works well with all high velocity .224″ bullets from 40 to 60 grains. Certain .22-250 rifles use a twist rate of 1:10 which usually functions best with bullets of 55 to 70 grains. Some target rifles with a 1:9 twist seem to do their best with bullets from 62 to 70 grains and particularly Sierra’s 69gn Match King bullet. Rifles with a 1:7 twist used for big-bore competition definitely prefer the heavier bullets of 62gn or more with some rifles shooting satisfactorily with weights of 80 and 90 grains. However, avoid using super-explosive bullets in the faster twists as the stress of a high rotational spin can cause such bullets to fragment in flight.