How can I measure the chamber length of my L.C. Smith shotguns?

Chamber length gauges are available from a number of suppliers such as Brownells and Galazan. These gauges are relatively inexpensive, but there is even a less expensive way to measure chamber length. Take a 3" x 5" index card, roll it lengthwise, slide it into the chamber (it will partially unroll and expand to the chamber diameter), gently slide it until it stops at the end of the chamber, use a pencil to mark the index card at the breech end of the barrel, and repeat the steps to see if it always comes to same spot. Then use a tape or ruler to measure length marked on the card. The chamber must be clean, and it works best with a new 3” X 5” card.