"The Swarm" by Wright's chokes is also what is in my wife's Mossberg 500 20 ga. I use it some as well. By far the best choke I have seen for a 20. They ship them out fast, too. I found that the 3" Hevi-13 #5 patterned the best for me with it. It stayed a bit tighter than the #6 Hevi-13. They both patterned better than any lead loads for me.