What does firing blanks on full auto do to a rifle barrel?

[Bret]

I was searching around and came across an NFA dealer selling some full auto AK's. The dealer states "From Hollywoods largest Prop rental business, this gun was used in films and has never been fired with live ammo Verification goes to the buyer." Assuming that they've never been fired with live ammo (a stretch), I'd guess that they've been fired with blanks. What would blanks do to a rifle barrel if anything? I don't know anything about them including if it's even possible to fire blanks full auto. I don't know if would even work given that I can't see how they'd cycle the action. I have purchased from this dealer once in the past and he seems to have a good reputation. At best these rifles have been handled a ton. Obviously if I bought one it would have to be restored. Scroll down to see the AK's.
https://www.davidspiwak.com/guns/

[mack7.62]

For blanks to work the action in semi or full you have to restrict the gas exiting the muzzle, the military uses an external clamp on fixture to do this but a movie gun does it internally. Depending on how this was done can affect how easy/clean it is to restore full function. If the gun uses a muzzle device like a flash hider you can do this there so just need to swap out, a bare muzzle many times they will thread the barrel for a screw in insert. Before I bought a movie gun I would make sure it was not done bubba style.

[308curry]

There's a guy that makes short barrels for semi auto Thompsons that can only use blanks. When mounted to the gun it itsn't considered an SBR because it only fires blanks.

But you're example I would say is still a machinegun.

[Bret]

I'm thinking that realistically these are only going to be good for donor receivers. Two are underfolders, which pretty much stink firing full auto, two have European side rails installed which are not correct and the remaining two are very heavily worn. I've seen some good work using donor receivers, but I'd be looking at another couple of thousand. For $26k you're close to buying a nice unmolested AK. I do wish he had more detailed information about the mechanical condition. If they're in excellent condition on the inside, it would probably be worth buying one. If the condition on the inside is similar to the condition on the outside, then no way.

[rjacobs]

I would NEVER, well I wouldnt say NEVER, but a FA anything without seeing it in person... I would buy a cheap airline ticket and fly out and see what I was buying. I wouldnt spend 20k+ on a car without flying out to see it, same goes for a gun...

The only place I might buy sight unseen is from Ruben Mendiola...

[TexHill]

It is my understanding that the reputable prop companies modify their rifles in such a way that they cannot accept a normal, live round. They do this to keep some jack wagon from bringing live rounds onto the set and killing a bunch of people. My guess is that you would have to have a new barrel installed as a result.

[Bret]

I didn't even think about that possibility. I'm glad I asked.