The M/16 was a relatively simple design. It was intended for static emplacement, and was mounted on a pedestal, allowing for 360° sideways movement. The mount allowed for an angle of elevation of between -1° and 75°. The gun barrel was 45 calibres long, and had 28 grooves (rifling) twisting to the right. The breech block was a semi-automatic horizontal-wedge - the gunner had to manually open it to remove the case from the previous shot, but it closed automatically on the insertion of a new round. There was a Hydro-pneumatic recoil cylinder under the barrel, with a heavy spring to aid the forward motion of the gun at high elevation. It was originally designed to fire under local command, but was later equipped to receive gun-laying information from a central sight.