Is it literally because they’re blank firing they can “legally” convert a semi-auto gun to full auto for filming purposes?
Mainly because I’m reading about how most MP5s you see in movies were civilian sold MP5s with extended barrels and semi-auto only, but movie armorers chopped the barrels and modified them to be fully auto in the 80s and 90s to look like real military MP5s.
Were the converted ones blank firing only? To get the action cycled on a gas powered automatic gun shooting blanks you often need a barrel restrictor/plug. Sometimes you also have to weaken the springs. If they welded the barrel closed and modified the springs the gun would be unable to fire real rounds.
That said, movies can get almost anything approved. And it’s not illegal to own automatic weapons, explosives, even tanks with main guns that fire. There’s a place in Vegas where you can rent all that stuff. You just need the proper training and licensing.
Most movie productions do not supply their own weapons. They hire companies that specialize in movie weaponry and have all the appropriate licenses. Those people deal with ATF constantly.
When making a movie, wouldn’t full-auto be all about the sound? If so, it seems the “tat-tat-tat” sound could be easily added during sound editing in post-production. So it makes me wonder how often a true full-auto rifle is used in filmmaking.
No, you also want to see some recoil, and flame from the muzzle.
There are shows that do this - use inert guns then CGI in a muzzle flash. It never looks right. The CGI muzzle flash doesn’t light up the surroundings, the gun doesn’t recoil, the actor doesn’t react to what would be a loud bang, etc.
Some automatic weapons for movies use propane to simulate weapons fire.’
No, a canny viewer expects to see the weapon cycling and ejecting brass. There are productions that have gone entirely to using Airsoft or other inert weapons and adding effects (the John Wick movies have all used inert weapons with post-production effects for obvious reasons) but they rarely look correct to an expert, although they have gotten a lot better, and with the deaths on the set of Rust, you can imagine that a lot of productions are looking at whether they really need even blank firing weapons at all.
I’ve known a handful of movie ‘gun wranglers’, and they get by with a combination of legal exemptions for certain types of non-ballistic replicas, renting or ‘borrowing’ real guns that are converted to fire only blanks, and sometimes just some clever trickery to make semi-automatic weapons appear to fire fully automatic. There was an episode of Miami Vice where there was an undercover agent demonstrating “Ingram MAC-10s” but the production couldn’t get actual full auto MAC-10s so they ended up getting some knockoff semi-auto clones and just filming the scene to make it appear that the actor was firing full auto, mostly by having the guns below the frame when camera is looking at the actor and then cutting away to the dummies he is shooting at that are squibbed to make it look like they are being hit by automatic fire.
Stranger
Heck, our local all-amateur Renaissance faire did (as faires often do) a Halloween show. One year, it featured mummies vs. Nazis, and they had little trouble getting blank-firing submachine guns.
Years a go I watched a low budget movie. When I read the IMDb entry it explained that not only did they not have special weapons, they couldn’t come up with blanks. So they used live ammo. There wasn’t a lot of shooting but in one memorable scene an actor is sitting on the ground with their back to a car while bullets are missing them and blowing out the car windows. The actor was cringing quite convincingly. I wish I could remember the name of the movie.
I would imagine that film/theater appropriate automatic weapons would be just fine. They’re not firing a projectile, and all they’re actually doing is making a lot of racket and throwing brass everywhere.
My suspicion is that those are well defined legally, and that filmmakers either can have qualified armorers create them, or there are prop companies who can create/rent them.