I was wondering if there was a simple way to make a squib to imitate gun wounds without having explosives in an actors shirt.
Two simple solutions:
1.) Plastic bag of blood with a fine wire/string stuck to it. Thread the wire through the wound hole in the shirt/leg/buttocks of the clothes, and yank.
2.) Lightly compressed air with a blood hose. Indy Mogul's first Backyard FX episode has a great video on building this kind of rig: http://www.indymogul.com/backyardfx/episode/BFX_20070611