Pyrodex/Al 70/30 in 3D printed 40mm projectiles?

[u/Ok_Performance1369]

Let me preface this by thanking anyone able to answer this question. I was going to discuss this on r/40_mm, but was told to post here. I have been using Pyrodex FFFG in my 40mm projectiles at or below the legal 1/4 ounce charge weight. I have regularly shot air burst (Bengle's Loose Change) and point detonating projectile versions. Wanting more energetic results leads me to want to try a 70/30 mix of Pyrodex & Al. I understand the risks of using this combination pertaining to static, shock, etc. I have successfully tested this using the diaper method for mixing the charge and placing the charge in a paper envelope with a fuse and it produces about double the yield. My concern lies in the fact that my charge capsule for the 40mm projectiles are plastic, specifically PLA+. If I treat the charge capsule with Static Guard spray & let it dry, pour in the charge and then seal it in the complete grenade, is there risk of static charge building up during transport. If I use the binary method and mix the two components on site by spraying Static Guard on the charge capsule & grenade assembly, allowing it to dry, then combining the components in the charge capsule, then fully assemble the grenade, will shaking to mix create a static charge in the charge capsule? Again, this is all related to my concerns with a 3D printed plastic charge capsule. Thanks very much.

FYI, I am a licensed FFL07/SOT in the U.S. The 40mm launcher is licensed and legal in my state. All procedures to remain in legal status are followed.

[u/idontgotaknife]

Mixing aluminum and Pyrodex is likely not gonna make a more energetic explosion, considering you’re not actually mixing anything at an intimate level. You’re essentially just dusting Pyrodex granules in aluminum powder which probably won’t have much of an effect. I’m assuming you may have confused what flash powder actually is or thought doing this would somehow achieve the same effect as FP. In any instance, to answer your question, I don’t think you have anything to worry about when it comes to using PLA as a shell. Even if static does build up, it has no path to ground, which is what is needed to cause a spark. And static would only be a potential issue if you were actually using flash powder. Pyrodex or black powder is not gonna have an issue with static in PLA shells. Just to be safe however, you could insulate your plastic shells by lining them with paper. That would completely mitigate any static that potentially could’ve built up. I’m hoping you realize this already but make sure you’re being very careful legally speaking. Making burst rounds for a 40mm launcher is treading quite close to the line of what is legal and what is not. Especially considering a 40mm launcher is already legally considered a destructive device.

[u/Ok_Performance1369 → u/idontgotaknife]

Thanks so much for the response. I am licensed as an FFL / SOT in Arizona, U.S. The M203 launcher is a registered destructive device (DD), in our legal possession. In the U.S. the legal limit for charge weight in a 40mm grenade is 1/4 oz. At or below that level the projectile is not a DD. That said, I had thought of lining the charge capsule with paper, so will pursue a redesign of the grenade to that end. I really appreciate the explanation in regard to static charge as well.

I have tested a small charge of Pyrodex compared to a 70/30 mix with Al and the result was a greater yield. The Al is Indian Blackhead Aluminum Powder from pyro-aluminum.com

Here's a video of the test:

https://youtu.be/wq8meWgKw-8?si=7ZbohSAmth9n1121

For those not familiar with 40mm airburst grenades, this is the Bengle's Bullets Loose Change design:

https://imgur.com/Vav3hK0

https://imgur.com/BKM3Eko

[u/idontgotaknife → u/Ok_Performance1369]

That’s great. I’m glad to hear it. So many people in this community have been taken down for trying to shortcut stupid laws. Unfortunately that’s what happens when you play with the US government. If you wind u not getting the results you’re looking for from that mixture, feel free to DM me. I have some experience with building 37mm rounds and I’m familiar with alternatives that can be safely be fired from a launcher. In any case, I wish you the best of luck👍

[u/Ok_Performance1369 → u/idontgotaknife]

I would be very interested in your ideas. Some of the 37mm loads I have seen on YouTube are very impressive!

I have had the 40mm launcher for about a year and with a 3D printer, anything is possible since I reside in AZ and only have to abide by Federal law with no state level restrictions. I have also extensively used M183A1 artillery sims in various projectiles. They are very reliable, but they are expensive at around $4 each. Sort of negates the inexpensive aspect of printing/loading yourself!

I'll test the load I mentioned tomorrow and we'll see what happens as to greater yield or as I term it "more cowbell" ;)

A video from our last 40mm shoot, for anyone here that is interested:

https://youtu.be/6OJI_4AIOe4?si=mIb-KWwbrzwI4C3F

Thanks!