Hi Mate, the preferred calibre for indoor rat shooting was always .25, but i have used hollow point and wad cutters in .177 with quite good results. i use an fn19 rifle running at 11.8 ftlbs (.177), dome heads can cause a lot of damage to property as these at short range can and will go straight through the target,never use pointed pellets you might as well use a 410 shotgun. Hope this helps