As it stands, at a CA firing range, I can't legally give to, lend to, or let a friend shoot my S&W M&P without a mag safety or any other safety because California has deemed the pistol, "unsafe" in "Roster of Handguns Certified for Sale" law,
PC 12125. (a) Commencing January 1, 2001, any person in this state who manufactures or causes to be manufactured, imports into the state for sale, keeps for sale, offers or exposes for sale, gives, or lends any unsafe handgun shall be punished by imprisonment in a county jail not exceeding one year.
So, if you felt bad about it, just say it's unsafe and against the law with the mental reservation that you're talking about Austrailian or British or maybe Californian law. If they press it, just say that you are liable and that your insurance is too expensive, already. Or ask them to cite
the Cal Penal Code 12126(c), (d) says:
has no safeties to prevent accidental firing... and magazine disconnect mechanism - that prevents a semiautomatic pistol that has a detachable magazine from operating to strike the primer of ammunition in the firing chamber when a detachable magazine is not inserted in the pistol".