He didn't pick up a gun though, did he? He picked up a prop. The fact it was an actual gun is irrelevant, he was told it was dead and would not fire any live rounds. You may say "it's basic stuff here in the US" to which I present to you some fellow Americans, how many of these people do you think would know how to handle a firearm?
(Ok, Red would definitely know how to handle a gun and was probably barred from having one for risk of shooting one of these dumbasses, but still).
Like I said, just because you and the people you hang out with know how to handle a gun, doesn't make it common practice. I'd imagine that the vast majority of Hollywooders, New Yorkers, and all the other metropolitan darling people wouldn't have a clue how to handle a firearm. Couple this with the fact that the company has literally paid someone to make sure it's safe, you'd expect it to be safe, no?
Clearly not. Perhaps my impression of the USA is wrong and Americans all know how to handle guns but that's certainly what American TV wants us to believe. The press on the other hand wants us to think you're all a bunch of murderous psychopaths who shoot up schools for lols. Neither of these is true obviously, but I think it's far from unreasonable to expect an actor (note: not a lumberjack or a hunter or an engineer or anything "manly", an actor. Someone who's had their every beck and call taken care of for the last 30 years) to now know how to handle a gun.
If he did know how to handle a gun, then the "armourer" (lol) wouldn't have been necessary.
Either way it's irrelevant. This conversation will go round and round in circles for the next month with you refusing to see it my way and me refusing to see it your way until we get bored, move on, and have the same discussion when Macauley Culkin's grandson shoots Miley Cyrus's cyborg grand-daughter in the fanny in about 40 years and end up bickering about it in rocking chairs.