MS09JackRadiationGunProjectile,
GammaGunProjectileLarge,
GammaGunProjectileSmall and
GammaGunProjectileSplitter01 (normally unused) have a Penetrates Geometry flag, which tells the game to alter VATS hit chance through obstacles with Penetrator, even though they're incapable of benefitting from said perk due to not being beam-type projectiles.