This image is an MBA 5.56/.223 so-called Ammunition Concealment Round, sectioned by Paul Smith. Like the earlier 40mm Cloud Seeding Rocket section, these came to me at the St. Louis International Cartridge Show (SLICS) 2011. The pics are not in my Gyrojet book yet, but will be in supplemental pages in work now for free download on my web site, Gyrojet.net. Do not look for them now (Thursday 19 May). It will be a week or so.
The 5.56 Ammunition Concealment Round was designed to be fired in an M16 rifle primarily or any other firearm of that caliber. I had an extra original stainless adapter with its 0.033-inch bore, an original .223 REM-UMC brass case with its head drilled out with a step to accept a .25 ACP REM-UMC NPE, an original 0.030-inch threaded Javette with its tundsten head (point) and threaded magnesium body (tail), plus just one original teflon gas check. I added a correct .25 ACP NPE and correct Bullseye propellant. (I had to buy a pound of the stuff to get the 0.108 grain I needed to complete Paul’s section.) I gave Paul the parts, and wondered whether he would be able to split the tiny 0.033-inch bore of the stainless adapter exactly. I shouldn’t have wondered. As always, his work is perfection, as you can see. When I got the sectioned cartridge from Paul, I added the Javette, gas check, and propellant for the complete round you see above. Very neat.
The threaded tail of the Javette carried either a less-lethal or lethal agent to either put a guard dog or sentry out of commission for a while or permanently, depending on the mission. Because of the Javette’s small size and velocity, the target usually did not know it had been hit. The teflon gas check also prevented the magnesium Javette tail from igniting in the bore from the burning propellant. You can see the step on the stainless adapter insert, which indexes on the bottleneck step inside the cartridge case. This prevents the adapter insert from leaving the case on firing. The design allows for reloading. See chapter 5 of the book for complete details.