The "pistol" has always been added by people not reading every word of the regs. It has never said "pistol cartridge". In years past when we could only use handguns for our center fire option, it read " pistols that fire a straight walled cartridge" therefore a 444 chambered T/C pistol was 100% legal, and the reason I bought a barrel....right before they announced the proposed changes, that have since passed. So to summarize, it is NOT, and WAS NOT "pistol" cartridges, it IS, and WAS "straight walled" cartridges.