We get this question 15 to 20 times every gun show we go to.
“Can I make the projectile explode on impact?”
Initially my answer is yes, but I always inform that person that it is about intent for whether or not the round would be considered anti-personnel. The best way to not get in trouble is to first register your launcher.
We have a video on facebook of a 37mm impact smoke projectile. It actually took a considerable amount of time working with my smoke mix to get a faster burning mix that still kept its color and could be used for an impact round or air burst. This will take you some time.
Why did we use smoke? We wanted the projectile to be a spotting and training round. Remember, it is about purpose, and the purpose of this is to train and to spot where it hit.
Now back to impact triggers. First of all we will not make them and sell them to you. The BATF&E tech branch told us NO and we listen then they say that, or else we couldn’t keep making cool things for you and us to play with. So the first design is the one everybody thinks of right away and I warn you to stay away from this as it is dangerous and you will most certainly hurt yourself and someone else.
This design is simple: it is a primer and a pin placed so that when the round impacts it goes off. Keep in mind what you have done with this round is make something that will blow up or go off when you bump it on something or drop it. This is bad juju. What I would recommend is a design that involves a setback trigger.
Keep in mind this is for informational purposes only and could be dangerous and or lethal if actually created. Do not attempt without a registered launcher and never use with something that actually explodes.
This is why we used smoke powder: the 37mm round used in our video combined a primer, a pin, a lead ball, a spring, and a hollow ink pen tube. In design, the pin and primer were at opposite sides of the hollow pen tube with the spring and lead ball in the middle blocking the path for the pin to hit the primer. When the projectile is fired, the setback of the launch pushes the lead ball to compress the spring and then drop into a hole cut in the pen tube this then freed the space up between the pin and the primer to make contact when the projectile hits the ground and compresses the cap. The cap would need to be weighted to ensure orientation upon impact. This sort of device would make the projectile safe until the moment it is fired.
Keep in mind anything can explode in the barrel, hurting the shooter, so never put anything into the casings that you wouldn’t want to blow up in your hands.
Another reason we used smoke: making a trigger that works can be satisfying just getting it right and making it function like it is supposed to. There is no real reason to use anything other than smoke for this 37mm round.