While it may be a mechanical issue with the firearm, this drives home the need to inspect EVERY round while loading it into the magazine. The checklist is shorter with a rimfire: is the bullet pointy end up, is the rim the same thickness all the way around and the same as other rounds?

We got centerfire ammo by the tractor trailer load. Over time we accumulated an interesting assortment of defective rounds. Bullets backward, primers sideways/upside down, bulges at the case mouth, no flash holes, no powder, revolver rounds with too thick/deformed case rims and the list goes on.