My best friend built a "Barnyard" gun in 32 S&W long for his daughter on a small Stevens rolling Block rimfire action. That can be converted to center fire, some easier than others. But for a shooting rifle, using available ammo makes a huge difference. RF ammo can be picked up ad hoc at gun shows, but people think 49 rounds in a beat up box is a collector item. I have a 38 Short RF revolver and manage to keep 40 to 60 rounds on hand pretty easily. Ivan