New to this pistol? Most of the time, it's the shooter, not the pistol. It will take hundreds of rounds to be comfortable with a new firearm. 124 gr is a good weight for a general purpose ammo. I use 125 gr reloads on my CZ 85 Combat and I am happy with the results. If you are using factory load, try 115, 124 and 147 grs. Choose the one the suits your shooting style. By the way, are you referring to a CZ 75 Shadow Tactical or a CZ 75 Tactical Sport? Is this a brand new pistol or a gently used purchase?