I see two possible problems with it. The broom handle is heavier than the original shot load. This may increase the pressure enough to blow up the barrel. The shortened shell may no longer seal the the back end of the chamber. This would allow the hot gas to escape through the back end. It depends on the gun what happens in this case.
Iīve seen photos of guns blown up both ways and the injuries that were inflicted on the people holding the gun. After that I would not try this at all.
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If it isnīt broken, it doesnīt have enough features yet.