You can convirt a 22 lr to a 22WMR/17HMR(for a ruger 10/22), the instructions are at rimfirecentral.com. I dont remember exactly what involved, but you will perminantly mame your gun. It is much more recomended to conver a ruger 10/22M to 17 hmr but very expensive. I would recomend you go and spend $250-300 and just buy a savage or marlin SS bolt rifle. Yet another option mught be buying an 80% receiver and converting that so your origional action stays unmolested. Now a 17hmr will be tough on small rabbits ans squirrels, and youd be at a point where for cost you could probably go to a savage 223 or similar. The WMR and HMR are great fun, but a 22lr has its place also, and i would keep it. Its hard to give up being able to plink 500 rounds for $10. The same brick of ammo is pushing $70+ at minimum. Id consider buying a few boxes of velociters and trying them out, they will be slightly faster than a normal 22. Tell me more? What is your use? And why?