hi,
i .17hmr will do the job fine of foxes, as will a .22lr. it is the shot placement that is important, head or chest shots are on as always. as for your sako quad, i know some one that has one of those and they had a .22lr barrel and a .17hmr barrel for it. it didnt work all that well. every time you change caliber it changes your zero. although somewhere i once saw a scope made for .17hmr's, cant remember what make it was though. good luck with the charlies