Starting with model 12, 308 Win, the bolt face is for 0.473" dia case base diameter and short action. That is a very versatile size. However, with a Savage rifle you can easily change bolt face. with your current set up you could easily change to several good varmint rounds including .243, 22-250 for example . With a new bolt head of 0.378" dia you could get into a host of 223/5.56 family of cartridges. You have literally dozens of options. Good luck - search on you tube for videos about the subject. In my case I have 3 actions and 6 barrels and another barrel on order.