I am in the process of deciding what caliber to rebarrel my Remington 700 BDL 30-06. The new caliber will be primarily used for varmit shooting out to 500 yds but also deer hunting for my daughter (she is 12). I am strongly considering the .243 with 55gr BT's for varmit and up to 105gr partitions for deer. I plan to use a Lilja 3 groove barrel but don't know the best twist rate. I am not ruling out other calibers, I just need suggestions to consider. Thanks for your help.