Carlson's Bismuth Bone Buster choke tubes are designed to produce excellent, dense patterns with all bismuth ammunition. The Bone Buster choke tubes are CNC precision machined from 17-4 heat treated stainless steel featuring a longer parallel section inside the choke over conventional factory choke tubes. Combine this with extensive testing with various loads and you have the perfect choke to deliver devastating patterns with Bismuth.FeaturesDesigned to be used with all bismuth ammunitionsBone crushing patterns Precision CNC machinedCan be used with all lead and hevi-shot loads