Wasnt it a barrel obstruction that was then shot out when he fired a blank with it? Checking to ensure it’s blanks in your magazine/chamber is fine, checking a weapon from a site armorer for barrel obstruction isn’t a routine thing to check. I certainly don’t check my guns for obstruction except when Im cleaning / taking out of storage / have reason to believe there might be one because of ex: a misfire.
If this was live ammo then so many people fucked up. No site I have ever heard of allows live ammo to be present at all. Most studio lots dont allow live ammo, and several in hollywood require security to use custom marked handguns that prominently say they have live rounds in them. Ive been told a few even have fully custom magwells for site security guards / lot cops so you cant swap the magazines around. The paranoia around gun safety in hollywood is nuts. It’s fucking incredible how many people had to fuck up to cause this.