I have seen this in a lot of movies and noticed it again now in "Taxi Driver". There is a scene where Robert De Niro cuts an 'X' into his pistol rounds with a knife.
I don't know much about weapons, is there any technical reason to do this? Does it somehow improve the ammunition? Does he do that to open up the round?
Or does it have some symbolic reason, like marking the ammunition in a personal way? What is this kind of scene usually supposed to tell the viewer? Is there any special meaning?