Abstract: An obturator for a projectile to be fired from a rifled barrel is provided in accordance with this invention, with this obturator being mounted on the projectile in such a way as to permit rotational slippage. A preferred form of our obturator comprises a ring of non-metalic material, which ring is capable of being mounted on a circular body portion of the projectile. An external portion of the obturator ring has a plurality of encircling slots, essentially parallel to each other, which slots are rearwardly inclined so as to define a plurality of chevron-like members designed to forcibly engage the rifling of the barrel. The interior of the obturator ring is designed to slip rotationally with respect to the projectile body portion as the projectile travels along the barrel, thereby advantageously minimizing the rotation of the projectile as a result of rifling effects.