I m 72 years old and since I was given a 22 when I was 13 and have spent a life time looked for the perfect varmint rifle. I m still looking . Learn how to reload and try different brands of bullets and velocities to match the varmint size and average distances you will be shooting then at. At close in shots the bullet my blow up on entry while at long range the bullet may pass in and out of the varmint with little damage. Over the years I have ben luckey and have used a 17 HM2, 17 HMR, 17 Fireball, 17 Rem, 204 Ruger, 22 LR, 22 WMR, 22 Hornet, 221 Fireball, 222 Rem, 223 Rem, 22-250 Rem, 220 Swift, 243 Win and have also used my deer-elk rifles a few time on varmints. Each round has its bullet weight, design, and velocity limits. If I were to go fox hunting and the expected shots would be within 300 yards with little wind the 17 or 221 Fireball would be in the pickup. But for some one new to the game start out with a 223 Rem and learn how to reload ammo. Get a good quilty rifle and scope so that you can get 1/2-3/4 inch groups at 100 yards. Have fun.