In the 1930s, the Ordnance Department developed a new bottom plate, which had side flanges that came up on both sides of the receiver and were attached by rivets. This fixed the problem of the original bottom plates, and became standard for all M1917- and M1919-series machine guns. While the US Arsenal at Rock Island was the leader in converting the existing stocks of M1917-series guns over to 1917A1 configuration, other arsenals took part. In addition, the rear sights were updated for the new ammunition and were changed to yards from meters, and also did away with the World War I multiple-aperture disk on the rear sight. The top covers also had a stronger feed pawl pivot arm installed, so the gun could handle the stress of pulling an ammunition belt from the ground. Rock Island Arsenal also developed an all-steel water jacket that went into production around 1943; this was stronger than the earlier brass-capped jackets. These steel components were interchangeable with the earlier brass ones to allow for repair of worn or damaged water jacket components.