Abstract: An extendible probe projectile and an extendible probe assembly therefor, in which the extendible probe reduces drag on the projectile in its extended position and is moved to its extended locked drag-reducing position by ram air action which is converted into a forwardly acting force on the probe during forward motion of the projectile.

Abstract: A cartridge case and cartridge arrangement and method in which a base is joined along an annular intermating chevron-shaped joint with a sleeve. In the illustrated and preferred embodiment the base is metal and the sleeve is glass-fiber-reinforced plastic. The case has a propellant, projectile, and a percussive primer. A plurality of circumferentially spaced vent holes are formed in the plastic sleeve along a portion of the chevron joint as an aid to reducing excessive interface friction loads at the chevron joint during firing of the cartridge. A less preferred modification and mode of practice of the invention is disclosed in which the base is formed of plastic material or a composite glass-plastic or other composite plastic material, and the sleeve is formed of metal. A further less preferred modification and mode of practice is disclosed in which both the sleeve and the base are formed of similar materials.