I've shot several Groundhogs with a Marlin Model 1894 in 44 Mag, using XTP bullets at around 1,500 fps. Let's just say that one bullet does the job in spades .... big time! Kind of like the eruption of Mount Vesuivius if you know what I mean. I also shot one with a Winchester Model 1876 in 45-60 using a 300 grain bullet at around 1,300 fps. Again, let's just say that 45 caliber flat nosed bullet generates a whack of hydraulic pressure. My favourite groundhog round, however, is a 32-20 90 grain bullet traveling at around 1,200 fps. Kills them dead. So if a tiny little 90 grain bullet that is only .314" diameter, does the job at 1,200 fps, you can bet the big calibers will do it even better .... that is unless you want to save the small game for food. I also once shot a Snowshoe Hare with an old .43 Mauser. That did the job alright. Once I shot a Racoon with a 44 caliber 256 grain bullet doing 750 fps. No problem. That Racoon never took another step. Bottom line: Big heavy bullets travelling at 700 fps or faster are bad news for small game.