Short light 223 bullets may explode on their way to the target if propelled out of a 1 in 7" barrel. My 1 in 8" barrel on my AR clone did that to 52 grain Speer hunting bullets. Only reducing the velocity and going to a better made match bullet allows me to be able to shoot those light short bullets. I stepped up to 75 gr HPBT Match bullets for the fast twist barrel and all is fine. I suggest that for a fast twist barrel you stay with the bullets designed for it, not varmint bullets designed for 1 in 10" barrels.
Longer (not necessarily heavier) bullets need a faster twist to assure they are fully stabilized. You can shoot shorter (often lighter) bullets in the faster twist if the bullets are made uniformly enough so as to have their center of mass coincide with their physical center of shape. Voids and poorly formed jackets can make that not true. The centrifugal forces can get so high with poorly made bullets (although quite adequate at slower rotational speeds) that they literally fly apart. Only shooting them will for sure reveal their deficiencies.
Note that the Greenhill formula gives guidance as to the required twist rate for various bullets. Bullet weigh is not in the formula but bullet length is as well as bullet diameter.