A precision guided munition with a fin assembly comprising a free spinning hub to which the fins attach addresses the need to roll control a projectile while eliminating the problems of the fin kit. The fin hub, to which the fins are attached, is radially decoupled from the mortar tail boom thus allowing it and the fins to spin freely relative to the body without coupling any of the spin. Advantageously, the need for a bearing between the hub and the tail boom is negated.