 Most non-toxic shot shells produce higher chamber pressures than lead shot and can severely damage these older shotguns and as a rule of thumb, use a more open choke than you would for lead shells.An example would be an improved cylinder choke will perform like a modified choke when shooting steel or tungsten shells.For such hunters, wishing to continue to use older shotguns with chokes not rated for use with steel shot, the use of bismuth shotshells in the place of lead shotshells is common.