An actor would be foolish to do something that might hold up the picture, or more importantly incapacitate him. If an actor does do a stunt he needs to make sure a stunt man stands by to see that it's done correctly.
“I don't have any ambitions as an actor. I felt very uncomfortable doing it. The first take every day I'd open my mouth and no words would come out. I'd do a couple of takes and eventually I could run the lines.”