I recently acquired four muzzle blast practice rounds made by Def Tec Corp. The manufacture date on them is 2000. They use black powder as a propellant, (30 grains of ffg), and an inert white smoke powder. To describe the rounds innards, going from the primer up, you have 30g of ffg bp, a thick cardboard wad compressed tightly onto the lift charge. Next is a thick felt “O ring” wad normally used to center propellant, however, this casing was the concave bottomed type, so it is not needed, and apparently used as a buffer to slow the expulsion of the powder a bit, and to keep the pusher wads straight in the casing on the way out. Next was another thick cardboard wad tightly compressed. Next was the powder, which looked to me like plain baby powder or talcum powder. Really loose stuff!! (I had to vacuum my keyboard again…) Really fluffy stuff! Next came two more cardboard wads, I don’t believe they compacted the powder however. I believe they were there to support the end wad, to make the end of the round sturdy. The top cardboard wad rested on top of the other two making a total of three wads on top. There was a layer of latex paint with MFG 2000 stamped in black ink on the top of the paint. These wads were approx 1/8” below the top lip of the casing (refer to attached diagram). As these are training rounds and contain smoke powder, they are legal to make and posses with unregistered launchers. You can also add cab-o-sil and OC dust to make your own muzzle blast rounds in the same manner. Just make sure you have a gas mask on when you fire them, as they tend to contaminate everyone in front of ad behind the launcher (depending on the wind direction). Here’s a photo of the round:


The overall length of the casing is 5.5” tall, and is made for 37 or 38 or 40mm launchers. I would imagine that Def Tec makes their OC, CS, and CN muzzle blast in the same manner, as this is a practice round, there were no ill effects of the white “smoke” as the wind was not favorable and blew it back at me, and I’m still writing this and don’t feel any… (I could use a drink however…) Here’s a diagram of how the round is constructed:

T-21 Diagram

As you can see, this is one of the simpler 37/40mm rounds to construct. It is one of the few that I don’t believe that ATF would have any problems with, being used in paintball games, as you are basically launching “baby powder” and with the proper eye protection worn during the normal paintball games, all that would happen is that you would cure any rashes suffered by your opponents, plus give yourself a pretty cool “smoke” screen. It is definitely not an anti-personnel round, and no injury would result from this round being fired in anyone’s direction, other than covering him or her with white powder. You do need to make sure that you use a powder that is not flammable however. Don’t use flour, or the like as it would explode like a silo, and probably frag you and your launcher!! The key is INERT powder. GROG