If that doesn't do it, get a shot of "would be criminals who fear for their lives or die learning the lesson."
If the mixed feeling remain, I'm sorry to have to be the one to tell you... it's terminal.
As I tell my liberal sister to really get under her skin, in my Utopia it would be illegal not to carry a gun and not to defend yourself. There would be high casualties at the start but the criminals (and pacifists) would get pared out eventually. Sometimes she looks at me as though I just might be serious.
I would just let this slide by were it not for the fact that I made it clear I don't object to a shopkeeper having a "choice", that is your word, not mine. I also made it clear that I support the 2nd Amendment. I will go a step farther and say that as a Missouri resident I'm extremely happy with Missouri gun laws and especially their further improvement under Governor Blunt.
The point I made, unequivocally, was that getting in a gun fight over $78 in your employers cash register isn't a particularly wise move. Now should you have a Constitutional right to do so? Sure.
I would think, however, that most employers would rather eat the $78 or file an insurance claim if it were a great deal more, than have to clean up their employees blood and call his wife with the bad news.