I guess I'm sort of an armorer - I filled that role (among others) on the set of a independent action film called "Thick As Thieves".

I had as many as 30 weapons on set at one time, and had to train all the actors in usage and safety.

They were all airsoft (mostly gas blowback) and we inserted sound and flash in After Effects.

It was much less expensive to go this route as opposed to getting the permits for blanks. Plus, we could effectively shoot and shoot wherever we wanted, whenever we wanted. Guerrilla filmmaking indeed. After the shoot, I also did the sound effects for the weapons, and a good portion of the foley work.

I would love to hear from a REAL armorer about their beginnings.