You did good BB , just because THEY FIT doesn't get it , there is a good chance that you may have saved him from getting hurt , I don't know of any shotgun that has a strait bored chamber , all of them have a forcing cone of one sort or another .
Not only did you probably save him from himself but you may have also saved the company and yourself from the lawsuite that came after he got hurt -- " The guy that sold them to me should have known better " thing .
Just take heed from the words of Ron White " You can't fix stupid "
stimpy