Any gun can get ring bulges if you shoot steel and:
- large enough shot;
- large enough loads;
- hot enough loads;
- wads with thin enough petals; and
- the gun has tight enough chokes.
And, of course, the less wall-thickness you have in the choke section of the barrels, the more likely you are to have a problem.
Screw chokes bring on a whole array of possible problems. They get stuck, they come loose and let gas get behind them, bulging the barrel. They get lost or bent out of round. It is true that all these problems are the result of mishandling, but I would say the same thing about shooting steel in a fixed choked barrel -- do it right and you will not have a problem.
P.S. That doesn't mean I recommend steel. It kills fine but is bad about breaking molars.
