I shot some of those minis years ago.
Tried to turn a fired one into a card holder for when I played Texas Holdem.
Neither my single stage or progressive MEC could crimp such a short shell.
Reloading them will not work on a MEC without serious modifications.
They're not really known to work well in most pumps. There is even a company that is making an adapter kit thing so they work better in the Mossberg, though I don't recall the product or the company name.