mr my deacts, im sorry to say that they 'Do' use live guns in films, usually section 5, when a scene needs it, e.g when mussel flash is seen, blank fire guns vent top/side in the uk, but due to health and safety rule the following rules apply.
1 deact used for close ups, loading revolvers, mags in autos, when any firearm is pointed at the head or chest its deact (somthing we should never do).
2 live arms are only handled by two people, the actor using it and the amour, blank rounds counted out and cases counted back.
3 background actors use wooden or for closer shot rubber.
4 any actor who is pistol whiped, or struck with a butt, its rubber.
5 a lot of the rest is move magic, and more cash more guns more bangs.
and as you say the 'best bren gun scene ever' if its deact what about the mussel flash, you big silly mydeact, or are you teasing us.
I dont doubt you, I just generally believe they are all made of wood. I guess theres a difference between UK and the USA also. I dont know much about muzzle flash etc. I would just have thought that the special effects and digital editing departments would handle all that. Just strikes me as logical as cutting real people when special effects will do.
Im not saying they dont at all other than in the blasie sense. I dont even know much about muzzle flash, never seen it.