The diameter of the shotgun firing pin will have to reduced for small riflle or pistol primers. The breach then will have to drilled and tapped for a bushing to fit the small diameter firing pin. The 22 Hornet barrel can be fitted by threading or pinning in a 4" stub of the bored out shotgun barrel. The shotgun extractor will have to modified to fit the 22 Hornet case rim. The other things required to complete the job; install sights or scope bases, re-fit forearm, and hone the trigger. This work will require at least a lathe and drill press. None of this is hard to do but it could end up being more trouble than the final product is worth. It is certainly not worth it if you will have to pay a gunsmith to do this work for you. One alternative is to get a Handi Rifle in 22 Hornet or one in 223 Remington and load cartridges to 22 Hornet performance.