Reduced stiffness barrel fired projectile

In various embodiments, a projectile includes a projectile body including a tail portion, a nose portion, a barrel engaging portion between the nose portion and the tail portion, and a metal jacket that defines an exterior of the projectile that surrounds an interior solid core. In one or more embodiments the projectile includes one or more circumferential grooves defined in the interior core portion, each of the one or more circumferential grooves covered by and positioned adjacent to the metal jacket and within the barrel-engaging portion. In various embodiments, during firing of the projectile, the one or more circumferential grooves define a void that allows material of one or more of the metal jacket and interior solid core to displace into the void for reduction in radial stiffness to the projectile in the barrel engaging portion.