The crimped-end birdshot .22 cartridges are actually designed for use in smooth bore guns designed to shoot them (they don't build them anymore). I have an old Remington (540 or 541? - I don't recall) which is a smooth bore and marked for shot cartridges only. It may or may not be choked, but it is relatively accurate and effective at reasonable (but short) distances. We used to use it on Starlings near the house. The #12 shot they are loaded with does not retain a lot of velocity over distances, and, if it is fired in a rifled firearm, the pattern opens very rapidly, rendering it ineffective at most ranges. If you are shooting from a rifled firearm, the Speer snake shot (in capsules) will be more effective.