in traditional one-piece rifle stocks, the butt also varies in styles between the "european" type, which has a drop at the heel to favor quick shooting using iron sights; and "american" type, which the heel remains horizontal from the grip to favor more precision-oriented shooting using optical sights. there are also in-between designs (such as the weatherby mark v) with a "halfway" heel drop where the front half of the buttstock stays leveled.