As far as I have understood from what has been written about this, is that 'cold' means it didn't have live rounds in it. Not that it had nothing at all in the barrel.
"Live" or "hot" means anything with a primer, with or without charge, "cold" means empty or inert. It could be that the scene called for dummy rounds to be used, in which case it would look loaded, but dummy rounds are commonly made with some way of easily telling them apart from the real deal (apparently the dummy rounds made for this film had pellets inside so that they'd make a very distinct rattling sound if shaken, and they typically don't have primers either.) In that case, simply looking through the gap wouldn't be enough, but if they were instructed on how to check whether the rounds are dummies or blanks, it would still be an easy thing to verify.
But yeah, it's not standard procedure, so there's no reason to expect he knew how, and he should have been able to trust that they guy who handed it to him had actually checked and was telling the truth.
Having grown up around guns my whole life, I would have checked the gun anyway… but not everyone grows up in the rural south and on a movie set, I would imagine that they’d expect firearms experts to tell them the truth.
What you’re coming off as here is kicking Baldwin while he’s down.
It's a terrible accident, and I feel sorry for him.
If I come off as insensitive, then I apologise. This is the internet, though, and Alec Baldwin is unlikely to come on here and create an account to view the CE forum, so I don't see the problem with trying to view the incident objectively and talk about how it happened, and what can be done to prevent something like this from happening again. This was clearly the result of a cascade of failures, and one should be able to acknowledge that much.
I don’t know what the loading gate is, I don’t know what the hammer is and wouldn’t fancy counting clicks and spinning cylinders, I’d prefer to leave it to someone who is trained and an expert.
And then even if I did learn to use this gun I doubt it’s the same procedure with different guns so then I guess actors should have to go on multiple courses for each different gun they have to hold. That’s a mess.
I don’t know why they don’t just use fake guns, I always thought they did to be honest.
It'd be easier if it was explained to you in person, with the help of a functioning example.
Most serious armorers demonstrate to actors how the guns work, and instruct them on how to use it before they allow them handle it. This is standard procedure anywhere where they're serious about firearm safety. What I'm suggesting is merely, in addition to instruction them how the gun functions and how to use it, that they are also shown how to check that it's safe when it's supposed to be. Reading all over the internet today, the consensus among those sharing their experience from working on film sets seem to be that it's always supposed to be the set armorer that hands the actors their guns, and it's also common to demonstrate to the actors that the gun is safe.
On your last point, non-guns and other less dangerous facsimiles exist. They have guns with the same moving parts as functional guns, that are powered by CO2, they have electric "non-guns" that simulate muzzle flash, they have resin replicas for anyone whose gun isn't meant to be shown up close. There's not really a need to use real guns in movies anymore, it's just done for "realism" and because it's cheap and easy.