cva's are made for powerbelt bullets. what kind of powder and charge are you using? the 245 grain powerbelt is an excellent bullet for 150 yard shots. i dropped 2 deer from 146 and 148 yards with my rifle a couple years back. i used 120grains pyrodex rs with a 245 grain hollow point bullet. A good placed lung shot drops them in their tracks. Theres no need for those huge bullets you mentioned. Another bullet you may want to try is either the 245 or 270 grain buffalo ballet. If your load and bullet is working for you now, just stick with it.