Minor point but the actor can;t always be given the gun directly - and might not even have sight of it before he/she gets hold of it
Imagine a scene where actor A comes in - actor B pulls out a hidden gun and shoots at actor A who falls but grabs the gun and shoots B
at which point actor c (the Hero) bursts through the door wrestles the gun from whoever and shoots the baddy
Now - at the start only ACtor A has the gun - and no-one can see it
Actor C has no sight of the gun and it is not in his control until he.she picks it up and immediatly pulls the trigger - at which point 2 other people have had control of it out of his sight
So they cannot do a safety check before pulling the trigger.
The solution is for all 3 to see the armourer check the weapon
after which the armourer is always positioned to see the gun - or have total sight of its position when it is hidden
and, of course, no live rounds allowed on set at any time and all weapons used in the film are kept secure and not used for entertainment at other times
not excessively difficult - but the American attitude to guns is way too casual - they probably treat their socks with more care than the guns - they seem to just consider them the same as toys at times