Are there any good video effect apps for guns and fire?

I just got a New app for stop motion video on my IPhone and I need effects too such as a shotgun, a flamethrower, a rocket launcher, ect.

Your doing this on a Iphone, most people use a full fledged computer, running a NLE to edit videos. They enough head over to http://www.detonationfilms.com/ to get stuff like that.