It’s stupidly easy to check a firearm. You don’t have to be an expert to do it. For most fire arms it takes 5-10 seconds.
A large part of the “experts” job is to know what is and is not safe protocol, and to enforce it. Part of that includes teaching everyone who’s handling a weapon how to…. Handle a weapon safely.
no question, the armorer fucked up. She’s human. Humans make mistakes. Which is why you check the damn weapon, too. An expert doesn’t mean they don’t make mistakes. An expert means they’ve made enough they should know better. (Or have learned from an older expert.)