well an AR can be set up for whatever type of shooting you care to do. There are better cartridges then the .223 for long range accuracy in an AR15 like the 6mm AR turbo 40. of course cheap bulk ammo is available in 5.56 that may be perfectly adequate for your varminting. i like my bolt guns. the only drawback i see for shooting prairiedogs with an AR is you will need even more ammo. Probably 2 or more uppers or you will melt it down.