As my dear old dad says, "I hate like h@!! to shoot a guy and then stand there and argue with him."
I would recommend a caliber that begins with ".4". Preferably a variation on the 1911A1.
That's pretty fair advice. But I like a caliber that begins with a *4* whether it's a handgun, something a bit larger, or even *just* a break-open singleshot.
And you'll have to excuse my ignorance, but is that an M-79 grenade launcher? I never saw one up close and personal.
A mugger would have a Cow AND Kittens if confronted with that set of personal protection, donchya think? :-D