Also how are you going to have enough time to look down and see if the gun that is pressed to your chest is a hammer or striker fire and say to yourself, let me try this new move I saw on YouTube
This definitely ain't for the average Joe. But with going to the range/shop often, actually holding different guns in my hand and watching model reviews and breakdowns and history of different guns I can identify a weapon by just a glance.
A lot of times tv and movies show just a brief glimpse of the gun or a gun before they show it firing and often the focus is either the muzzle flashing or the victim getting hit and exploding (Tarantino movies) or something else.
Usually movies and TV just show a glimpse of a gun just to show the character has a gun, but with my knowledge I'm able to identify guns with almost encyclopedic knowledge.
It's funny cause on investigation discovery between the actual evidence/police photos and the re-enactments they rarely get guns right. They'll show usually the re-enactment character will have a shotgun, regardless of the model or make, but the voice over will be like "the victim was killed with a 20 gauge shotgun" and if you know, the stock gun the character is holding isn't or doesn't make 20 gauge.
They often switch up striker fired and hammer fired too.
It's like that when this is a hobby.
Some Nike dudes can look at the imprint of a shoe and tell you what shoe it is, I work with a cat who can identify and tell you anything about in railroad, train, train car in America and likely all over the road. He knows all the lines, the history, who made them etc.