... when I go into a gun store it's clear that there is some kind of protocol that I never knew about, and once I break one of those rules, the hammer is coming down. It's like the guy across the counter is testing me by observing my actions.
Exactly. A lot of people who are shooters can tell pretty quickly who knows how to handle a weapon properly and who doesn't when they see someone holding a gun. An inexperienced person with a gun can be pretty dangerous without meaning to. In a store they can unwittingly damage guns by mishandling them too. That's why the OP caught hell over that revolver.
Plus, gun sellers tend to be far less shy about being judgmental about strangers than average. A clean cut, well mannered individual will invariably get better treatment from them than someone who has lots of visible tattoos and piercings, a weird hairstyle, or wears clothes that are too much like what outlaws wear. Some people have complained about this, but it's a fact of life. Gun dealers will paste a mental label on you the moment they first see you, and you control what that label is by how you dress, what is stuck/inked in your flesh (and where), and how you comport yourself. Everyone else does it too, but it's less obvious since you're not asking them to sell you a deadly weapon.
The dude opened the cabinet, took out the gun, removed the magazine and locked the slide open, then handed it to me with the trigger lock still on it. I thought this was a very odd way to be evaluating a gun! Could I ask to remove the trigger lock? Was that some kind of protocol I didn't know about? Why did he lock the slide open? Can I close it? What am I supposed to be looking for here? Frankly I was unconcerned as to the internals of the gun. I needed to know how it felt in my hand (which would help if the trigger lock were off, the magazine was in it, and the slide was closed), how it compared to others like it, etc. Suffice to say this visit was a little off-putting.
Some of the people behind the counter selling guns know little about guns and shooting so they will do things like that. This is common in chain retail stores since these types of retailers basically stick employees behind the counter with the bare minimum of expensive training time. In a gun shop that usually means the guy is a jerk.
Kind of like, "no, of course we don't carry that gun you moron. It's a piece of crap. You can't buy a decent gun for under $xxx, don't you know that?" only with a lot more 4-letter words.
The gun subculture is full of people who can't tell the difference between opinion and fact. Unfortunately, some of them take their "facts" so seriously that to disagree with what is really their opinion is not much different from insulting their religion.
I ended up going back to the same shop and this time there was a different counter attendant and when I asked to see the gun he did what I would have expected the first guy to do. Removed the mag, checked the chamber, closed it back up, removed the trigger lock, and set it down. I bought it.
I bet that guy knew more about guns than the first, had done more shooting, and was a better salesman of firearms.
After my first week or two of owning a gun, and after going out and shooting this gun and a number of others, getting real comfortable around them, I went into another gun shop and asked to look at a gun behind the counter. This time I knew much more about what I was doing and I am sure I projected a lot more confidence. The guy behind the counter handed it to me and then began to discuss the relative merits with some other guns, took out a couple more competitors to this one just in case I wanted to see them, I asked if I could dry-fire it to check the trigger and he grabbed some snap caps ... whole different experience. I think a lot of it has to do with the way I felt going in, and how I must have appeared in attitude.
Looks to me like you had crossed the line from noob who deserves no respect to someone with a measure of expertise. Yes, it's true: In this business the customer must earn the respect of the merchant and not the other way around. But it could have been that the guy in that shop was a much nicer person to deal with. Lots of gun dealers are incorrigible jerks.
Anyway the point is, there is kind of a gun "clique" that I can discern, and I am pretty sure I don't want to be in it, but it is not exactly inviting to newcomers.
Yes, there is sort of a gun clique. It isn't always inviting to newcomers because all too many people want to be in it because they crave the respect that an extensive knowledge of guns can get them from their peers but don't want to actually spend the time, effort, and money learning about firearms. People who run around pretending to be firearms experts generally piss off the real experts. You may find yourself part of the gun clique in the future simply because you know about firearms and some idiot in your presence is opening his/her mouth (or worse, handling a gun improperly) and proving his/her ignorance/stupidity/craziness.