Man, that is vague in the description department, I have a 3d machine gun code that someone wrote for me, but I need to go find it again.
First off, is the game 2d or 3d, is it a first or third person shooter (view,) what is meant by machine gun effect, do you want a rapid fire gun, a flash of light of the gunpowder going off, or the marks it leaves on the wall.
Its almost impossible to help you with that description. I wonder if this is another hit & away posts that this forum gets quite frequently.
Well, im going back to modeling my ingame player models for my game, I will try to post some screenshots in the team request forum at some point when I get more.