Carlson’s Sporting Clays Choke Tubes are made from a 17-4 stainless steel and precision machined to produce better patterns. The 25% larger parallel section in the choke throws more consistent patterns than conventional choke tubes. Lead, copper plated, nickel, Hevi-Shot, bismuth, tungsten or steel shot can be used in these choke tubes. Steel shot larger than BB should not be used in any Sporting Clays Choke Tube tighter than Full Constriction. For best results, Carlson’s recommends patterning your choke tube with the specific shotshell you will be using in the field.