Rather than create the content of my own blog, I'll use the comments from other people's blogs. We have done many experiments with explosive-less squibs. I like the idea of the actor actually controlling the squib's timing. Here's Bill Martell's comment on his own post regarding his movie experiment.
Because I saw THE WILD BUNCH at a tender age... buy some aquarium plastic tubing. Buy one of those lens cleaner bellows things at the camera store. Buy a piece of aluminum tubing, bend it at a 45' angle (you'll need one of those coil things to bend tubing - I built model cars and had stuff like that). Bellows to plastic tubing to aluminum tubing to and old belt with alum tube poking out belt hole. Fill with fake blood - you want thin blood, more water than syrup. Belt goes under costume - slice little hole for alum tube to peek out. Plastic tube goes down leg. Bellows is under acror's shoe.I don't really know what kind of aluminum tubing he's talking about here. But I dig the idea overall. I think we've tended to use blood that was too thick. That's been a problem. So we'll thin the blood now...
Now place actor out in the open - away from everything.
Take another actor with plastic gun that flashes - put them across from blood rigged actor - high noon style.