Certain Calibers/Rifles are good for specific types of Hunting and different size and types of Game Animals...some caliber Rifles are good for several different size Animals.The 30-30 Caliber Rifles are great for thick brush and shooting distances of 50 to 150 yards or better if You can use the newer Lever_Revolution shells/bullets from Hornady,The 30-06 Rifle is great for longer distances and bigger game animals from Hogs,Deer to Mule Deer and Elk...the .308 is another good High-powered Rifle that can take down Big Game Animals and shoot long distances.Another thing to consider is the different grain weights available in the 3 mentioned calibers,a lighter bullet will travel faster yet it can be caused to glance off target if it happens to hit thick brush,tall grasses,limbs etc...!Lots of different variables and things to consider when choosing a certain Caliber Rifle and what You intend on doing with it...will You be target practicing,hunting smaller game like Varmints/Predators Coyotes etc...or will You be hunting Deer or bigger Game Animals?