A representative reverse-saboted sidearm system includes: a sidearm having a barrel assembly with an inner wall defining a longitudinally extending bore; and a round of reverse-saboted ammunition having a non-necked casing, a reverse sabot, and a projectile, the reverse sabot mounted at a discharge end of the casing with a distal end of the reverse sabot extending outwardly from the casing, the reverse sabot exhibiting a diameter corresponding to a diameter of the casing and defining a receiving passage aligned with a longitudinal centerline of the casing, the projectile being at least partially disposed within the receiving passage of the reverse sabot; the inner wall of the barrel assembly being configured to engage an exterior surface of the projectile to direct the projectile.