What size shell does a faultless 12 gauge use?

A faultless 12 gauge shotgun typically uses 2¾-inch or 3-inch shells. These sizes are standard for most 12 gauge shotguns, with 2¾-inch shells being the most common for target shooting and smaller game hunting, while 3-inch shells are often used for larger game and waterfowl. It's important to always check the manufacturer's specifications for your specific shotgun model.