I just made 2 sets of 10 to 20 ga inserts and will test them this weekend. If all is good I will offer them for sale. After that I'll get started on 8 to 12 ga.
I am doing this because it will allow people with these big bore guns to shoot them more often, at clubs that don't allow them. They can hone in on their shooting and save the
more expensive shells for when they wish to actually shoot them.