What is the most useful obsolete cartridge out there? By obsolete, I mean a cartridge that is no longer being chambered in most new rifles. And by useful, I mean it could and should be around today based on its performance against a similar cartridge that may have run it out of town. The 30-40 Krag immediately comes to mind. 300 Savage? Maybe the 32 Special. I feel like I'm just scratching the surface here. 6mm Remington is another. You tell me.