Special effects can be intimidating for new filmmakers, especially if they do know how special effects are created. As with magic, special effects seem mysterious to spectators, who do not know the secrets of creating them. Gunshots are some of the most common special effects used in movies. There are several methods of accomplishing this effect. Some of them are expensive and dangerous, especially if not done by professionals.
Make fake blood. Pour a tablespoon or two of flour, 3 bottles of food coloring and one gallon of water into a bottle and mix well. A gallon of this will last a while and make over a dozen gunshot wound effects. Try to get it to the dark red color of real blood but not too dark.
Fill a latex condom with the fake blood and tie the open end into a knot. Do not overfill the condom or it could burst. Do not under fill it or the blood will not burst out with enough pressure to gush outwards.
Tie about 10 feet of fishing line to a metal washer. If the scene is to be shot outdoors or in bright light, use strong black thread instead of fishing line because fishing line will reflect bright light and be viewable on film, which will ruin the whole effect.
Glue the washer to the condom and press in firmly and allow it to bond. The washer and glue will severely weaken that area of the condom on which it is glued. The gunshot wound apparatus is now complete and ready to be put into action.
Cut the film shooting right before the gunshot scene is to be done and setup the gunshot "victim" with the condom. As an extra way to make the gunshot look more realistic, time the cut to be while aiming in a different direction than that of where the victim is to be shot. This way, the transition will not be seen and it will be a clean cut with no chance of being noticed on film. If the gunshot scene is to take place immediately after the cut scene, try to have the gunshot ready to setup as soon as possibly, especially if outdoors or near windows because you do not want the lighting to change and ruin the transition on film.
Prepare the victim, be it actor, mannequin or something else. Tape the condom to the "victim," under his clothing where the shot is to appear. The chest is the obvious choice. The thighs and back will work too. This effect will not work for gunshots to the head because the condom cannot be concealed there, unless possibly under a hat. Cut into the clothing, right over the condom, so that the washer is uncovered. Fold the clothing lightly over the condom and washer, so as to hide it from camera view.
Tie the loose end of the line or thread to a small piece of wood or anything that can be used as a handle. This will give a firmer grip to the person who will pull the line. The person, who will pull the line, needs to stand off camera, so that they cannot be seen on the video or film. Once in position and it is confirmed that the line cannot be seen on film, roll the camera again.
Pull fishing line really hard and fast and it should tear clean away from the condom, rip a hole in it and blood will gush out in a stream. The washer and glue will have weakened that area of the condom severely weakened, making it easy to rip open. The washer needs to fall away quickly so as not to be seen on film.
Add the gunshot sound effect with a few different methods. One way is to have someone shoot a real gun or cap gun into the air at the exact moment the line is pulled. It can also be done with an audio recording, if it's high quality. However, this requires perfect synchronicity with the tearing of the condom, which might not always work. Another method is to use a video editing program, such as "Virtual Dub," to blend the audio of a gun shot into the actual audio from the film beginning at the exact frame before the line is pulled. It will only last a few frames but is a lot more accurate than the first method and can easily be redone until it is just right without needing to redo the wound.