Smaller shotshells (such as 20-gauge shells), if mistakenly fed into a 12-gauge gun, will slip past the chamber and lodge in the barrel, causing serious personal injury or gun damage if a 12-gauge shell is loaded and fired. Some rifle and handgun ammunition also may fit into the wrong gun, creating a dangerous obstruction. The caliber or gauge stamped on the end of the shell must match that which is stamped on the gun barrel. Some barrels are not stamped. Be sure the right ammunition is used in your gun.