What I have seen is the barrels not made for steel shot will ring in front of the choke. If there is a vent rib often it come loose. That is with Browning's and Remington's , they have cut chokes . Single shots often have swaged chokes and they get the choke spread out with enough shooting. I have seen barrels with groves cut in them from steel shot going thru. them. But I have not seen one blown apart. When steel first came out there was little or no protective shot cups todays steel loads have good protective shot cups some with bag type sleeve to protect barrels. Newer barrels are stronger and thicker and resist ringing . I have an 870 with a fixed full choke that has had hundreds of steel loads thru. it with out damage. One option is to have an extended choke installed and it will work fine on guns with thicker barrels.
