That compressed air method of the squib hit works great to on that site, I built a tank from PVC using the same concept and was very happy with the results. So check that out to if you need to have some one being shot.
The recipes on the exposure.co.uk site are OK, but you have to use a large quantity of food coloring to keep it from looking watery and pink. Do you need a lot? If you only need a little, and have a devoted cast, ask the actors to actually wound themselves
I use "Cinema Blood" that I bought in an 8 oz bottle from the local costume and stage store. It wasn't cheap - maybe $10 - but the bottle has lasted me for a while. For gunshots and splatters, I use the homemade crap, which is basically corn syrup (I use Karo) with food coloring and a little detergent. You can also alter the consistency with water. The recipe on the site may mention adding blue - you need a very small amount, or the blood becomes purplish. The blue is proportionally much stronger than red. If you want venal blood, maybe 1 drop of blue per 15-20 drops of red. For standard arterial blood, I would say half that amount of blue.
I've never used the compressed air like on that site - it sounds pretty good but I don't have an insecticide sprayer, so I would probably have to rig some kind of switch. For gunshots I have used the old fashioned fishing line method, where the blood pack is the finger of a latex glove or a condom, depending on size. I superglued a washer to the outside and tied the line to the washer. Tape it to your actor with gaffer or duct tape (under clothing, with a small X cut in the cloth), have someone off screen holding the line in the correct position, and yank it hard. Blood splatters out and it also makes the clothing briefly puff outward like when someone is actually shot.
Thats pretty cool, I should try that. But for my detailed hits I built this cool tank out of PVC that you pump compressed air into it (like a basketball). Works pretty good.
Gaffers Tape can be used for pretty much anything on a film set, you'd be surpirsed how often you end up using. It's always the right answer. But it's even more uselful when you're shooting on film instead of video. You tape the edges of the camera up to make sure you don't get light leaks on the film. Gaffers tape is great beacuse you can use it on hot things like lights and it doesn't get gooey like duct tape.
You can get it at any crafts store or home depot, but it's pretty expesive, like $15.
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