Another possible issue with shot shells is they can break open and the shot will be in places besides the barrel. A friend many years ago loaded 44 shot shells in his 1894 and one sprung a leak jamming the works.
They're best when shot from revolver, single shot, or manually operated rifle and within 10' at the max. The .22LR shotshells are very tiny (#12) and lack penetration. The CCI are better with their plastic enclosure than the crimped kind. The crimped case is too long after uncrimping to eject manually through most semiautos. The CCI .22 mag shotshells are better as they contain a larger amount of #11 shot, but are still at their best within very close range.