An abrasion collar is usually found in association with a contusion collar of bruising caused by damaged blood vessels in the skin by hydrostatic forces from the bullet's entry.[3] An abrasion rim defect is also possible in firearm exit wounds under certain circumstances, such as if the skin at the exit was crushed between the outgoing bullet and an unyielding object pressed against the skin over the exit site, or if the projectile exits at an extreme angle. Careful examination of the wound under magnification may show signs of everted (outward-turned) edges characteristic of an exit wound.[4] Multiple projectiles impacting in close proximity together, such as in a close-range shotgun blast, will usually still produce an abrasion rim or artefact, though the wound will likely be irregular in shape.[3]