On a standard 12-gauge barrel, the inside diameter of the tube is .730 inches. Choke measurements are based on differences. This is often where hunters become confused when talking or choosing hunting chokes. To make this easier to understand, look at this chart. The chart shows the size o...
MINIMUM BARREL OUTSIDE DIAMETERS CHART* *These measurements can be taken with calipers or a micrometer 12ga. REM-Choke .850 12ga. Invector/Win-Choke.850 12ga. TC Std. .825 12ga TC Thin-Wall .805 16ga. TC.750 20ga. TC.705