Do you want the pelts, or do you just want them dead?

If you want the pelts, I'd go with a bullet designed for deer sized game like a 95 grain Nosler Ballistic Tip or Hornady SST. If you just want to kill the little b*****ds deader than a doornail right now, I'd go with the 55-75 grain Nosler Ballistic Tips, which are the varmint versions designed to virtually explode on impact.

Mike