Homemade Electronic Toys How Can I Put Gun Effects In A Homemade Gun?

How can I put gun effects in a homemade gun? - homemade electronic toys

I have the sound of machine gun with a rifle as I do, not the assault rifle from Halo. How can I do not seem ridiculous? I always thought another toy gun and laid it there, but looks like something because they are too childish. Any help? (Must address so I can make a detour)