[zippy13]

Let's not forget the typical constrictions mentioned are for 12-ga guns. Where 0.040" is a superfull choke in a 12-ga gun, it takes only 0.020" to do the same job in a .410-bore barrel. Here are somelinks to Briley's useful choke data:

1. Sporting Clays Choke Chart.
2. Choke Constriction Chart.
3. Hunting Choke Recommendations.
4. American to European Conversion Chart (12-ga).
5. Star Markings.
6. Lead to Steel Shot Conversion (12-ga).