So you personally inspect your car for suitability, your food for safety, all amusement parks, buildings, tools, etc that you come into contact with? Yes, modern society would not be possible without outsourced responsibility.

>Negligence does not differ for actors.

Of course it does. Those with more knowledge and training are held to higher standards in specific contexts. That's why we have licensing and such. The question is how do guns fit into this context.