The bulletIS the projectile. A cartridge consists ofcase (or brass as we handloaders call it), primer, powder and bullet. Two differentcartridges can utilize the same exact bullet (projectile).For example,a .308 Winchester and .300Weatherby mag both use 30 caliber bullets. The Weatherby has a larger case, therefore it holds more powder and can launch thebulletsquite a bitfaster and, therefore, farther. I'm not sure what you're trying to achieve because you haven't really said, so I guess I'll leaveyou withthis: if distance is all you're interested in then buy a rifle chambered for a cartridge that utilizes the largest case for the caliber of bullet you want to shoot.