Hello and welcome onto the site!! I dont think either of those calibers (.22rimfire or a .17hmr) are suitable for fox control on a regular basis. theres just not enough power to them. The .22 is an ideal rabbit and small vermin gun and the .17 is similar but obviously with a greater killing range, I find them great for those wiley old corbies! The reason I dont use my.17 is because the bullet is likely to stray a bit in windy conditions, therefore wounding foxes, as to kill a fox cleanly with either calibre a good head or heart shot is a must! Therefore a .222, .22 centerfire, or even better