Firstly A/C I would have done exactly what you did except I would have had the sales person totally repremanded and possibly fired for his actions. I would not have just walked out. I am the customer and will not be treated that way or spoken to like that by anybody!
Secondly in regards to the fellow shooting the gun in the store.... I have never had a handgun passed to me in a gun shop that was not cleared/checked with the action, slide, cylinder left open before it was passed to me.
Total negligence by the clerk and the customer.