just completed the scope selection vortex pst 2,the mount egw, the rings arc m10. cz550 tacticool 308 1-12 twist,26 inch barrel.using only factory loaded ammo, start with prime 175 grn, gold medal 175 grn, any other suggestions to include? working my way to 1000 yd, any help and advise would be wonderful. is 20 rounds each ok for seeing what the gun likes best