Finding the Correct Ammunition for Your Shotgun
To find the correct gauge and shell length, look on the side of the shotgun barrel. Generally, you will find the gauge and chamber length stamped on the barrel. This is true for all new firearms, but older firearms and custom firearms may not have such markings. Make sure you check the gauge and shell length of your gun before you shoot it, and use only the correct ammunition! If you are unsure of the gauge or chamber length of your shotgun, take it to a gunsmith to check.
Shotshells almost always have the gauge stamped on the base. Information on shotshell hull length is found on the shotshell box.