Abstract: A self-opening lens protective device for protecting the lens of a scope mounted on a gun is disclosed. The lens protective device is comprised of a tubular sleeve member having a first end thereof adapted for mounting on an end of a scope and having a second end for mounting a cover member thereto. Relative to the barrel of the gun when the protective device is placed on a scope attached to a gun, the tubular member has a top portion furtherest away from the gun barrel and a bottom portion closest to the gun barrel. A cover member is pivotally connected to the second end at the bottom portion of the tubular member and is adapted to open by gravity when the gun is brought to the firing position.