Our only restrictions are no green-tips.

I wonder if by green tip they mean anything penetrating, or if they specifically mean green tip (correct me if I'm wrong, but doesn't the green tip indicate barrier penetrating capability, but only for a specific brand?)

Yes, green-tip is the marking for steel core, but not all steel core ammo have their tips painted green. Sorry to hear they do it to you.

Im sure its a liability issue. Luckily I work for a department where we are not issued our sidearms so there are about 5 makes we can choose from and several different calibers. Most city police departments issue .40 cal, which in my opinion is an underpowered round, because it reduces the risk of over-penetration and lawsuits against the department. Law enforcement has become very liability-focused because people LOVE to sue cops and their departments.