Howard over at Loose Rounds often posts some interesting things and this post, in particular, caught my eye as something worth looking deeper into. It seems that Howard is in the process of trying to make DIY 40mm practice rounds for his launcher. Howard owns an M203 40mm grenade launcher, however, genuine practice rounds are no longer easy to come by ever since the ATF deemed them as Destructive Devices back in 2015.

DIY 40mm Rounds? Loose Rounds attempts to 3D Print 40mm Projectiles

DIY 40mm Rounds? Loose Rounds attempts to 3D Print 40mm Projectiles

One of Howard’s first attempts was a fully 3D printed projectile from top to bottom which fits inside of a practice case. This seems like a logical first step, personally, I would be worried about the projectile being too light. Either way, the round was tested out and found to just blow apart when the round was fired.

The blown apart projectile.

Next, Howard 3D printed a hollow projectile which he then filled with wax. He used simple candle wax purchased from Hobby Lobby and then melted the wax and poured it into the cavity at the top of the grenade. I assume this accomplishes both adding weight and possibly providing a bit more structural integrity.

Note the wax filling in the middle projectile.

This attempt, however, was not very successful either and according to Howard, it created a disastrous mess both inside of his sink as well as inside the launcher tube. When fired, the wax center blew out leaving behind what looks like pieces of the plastic housing as well as the wax. In his words “That was not fun to clean out.”

DIY 40mm Rounds? Loose Rounds attempts to 3D Print 40mm Projectiles

The wax shrinks about 10% when it cools inside the hollowed-out shell giving the top of it that concaved look. I’m assuming Howard will have another go at making 3D printed 40mm rounds and I’ll be interested to see where this goes. If he comes out with something reliable and possibly reusable I’m sure there are plenty of M203 owners out there who would like to get a hold of his file for their own printers.

All images obtained from Loose Rounds.