From everything I have read, for the .25 bore cartridges the 1 in 10 is recommended for bullets up to 100gr and a 1 in 9 for anything heavier. There are several variables that come into play with twist rates however. Velocity of the bullet, length of bullet, barrel length as well as a couple others, all effect twist rate and bullet stabilization. Also, every barrel is different - one barrel with a 1 in 10 might shoot 120s just fine while another won't. The recommendations are just guidelines so you'll just have to try a few of each weight and see what your barrel likes. A good compromise would be the 110gr Accubonds, should work well for yotes or deer. Good luck!