I have the R9 in .177 calibre and have been able to shoot even the biggest Magpies out to 70 metres without problem. Just a puff of feathers and gone! I sight the rifle in at between 37 metres and 46 metres (measured) beforehand. I use a heavy pellet H&N Barracuda Match for the long shots and for closer shooting use a lighter pellet. We don't have jack rabbits here but I have shot the occasional feral cat out to around 40 metres. Pellet choice will make all the difference whether you shoot a .177 or a .20. Although I have the .177 calibre rifle I think I would probably go for the .20 for a decent one shot kill. It's a pity we can't buy the .20 calibre here in NZ, just the .177 or .22.