Yes - I have to agree, the 10mm would be good for an auto.
I have or would have a more faith (for me) in my 4" M29, though, with my 275gr. hardened SWC at 1,210fps. It's comfortable and easy for rapid fire (or was last time I shot it) - it's been a while now. Kind of a moot point here - can't carry it anywhere, now.