When I was about 13 years old a kid down the road made a fairly common practice of taking his pen knife and cutting fully around and half way through plastic shotshells just at the bottom of the shot charge which allowed the full front portion of the shell to exit the bore. (I DO NOT RECCOMEND THIS!). He got very tight patterns as was evidenced by the door of his mother's mobile home the day he had an accidental discharge with his shotgun. I remember thinking it looked like he had used a rifled slug! The pattern inside of the door was much wider as it completely peppered the entire interior of the bathroom! As result I have always though that a shotcup without petals should throw tighter patterns than those that spread open as they fly? I don't know if one could tape the petals together safely or not for such an experiment?
