I got these pictures from the excellent Colt Ar15 Resource facebook group. Below you will see three original boxes the 5.56Mm duplex rounds. The ammo is loaded with two projectiles in each case. The idea being it increases your chances of a hit. When fired on full auto the idea was to double the amount of lead in the air. The ammo was intended to be use in one of the project rifles. Obviously it didn’t go anywhere.