That is the percent of shot that will stay inside a 30 inch circle at 40 yards. Table of percentages below for 12 g. Percentages remain about the same for other guages. although the measurement of constriction would be different.Standard American*Constriction (12 gauge)Pattern percentageCylinder.000 in40%Skeet.005 in53%Improved Cylinder.010 in57%Modified.020 in67%Improved Modified.030 in73%Full choke.040 in75%
Mainly the degree of choke, or constriction at the muzzle. a skeet choke is the smallest degree of constriction next to no choke at all (cylinder bore). Hunting shotguns may be full choke, modified, or some other combination. The greater the degree of constriction, the greater percentage of pellets kept in a small circle. Cylinder.000 in40%Skeet.005 in53%Improved Cylinder.010 in57%Modified.020 in67%Improved Modified.030 in73%Full choke.040 in75%