New, Old Stock Gas Cylinder Lock. This is late WWII production approx June 44 on thru the 1950,s. This was the first tougher gas lock produced for the grenade launcher. The early beveled type had a tendency to crack at the top, these won't, they are heat treated. They are easy to distinguish from the early type. They have no bevel on the forward face and are stamped with an "M" for Modified. This is a great all around gas lock for shooter and collector alike!!