Twist rate on T/C .223 is one in 12 , It is common . I know of several manufactures that use the same . It will stabilze bullets up to to 62 grains depending on velocity but best results are usually with bullets in the 40 - 55 grain range .
The ability to stabilize a bullet is determained by the velocity and length of a bullet not the weight but manufactures dont give the length of the bullet .