Initial designs suffered from the potentially catastrophic problem that friction between the shot and black powder during the high acceleration down the gun bore could sometimes cause premature ignition of the powder. Various solutions were tried, with limited if any success. However, in 1852 Colonel Boxer proposed using a diaphragm to separate the bullets from the bursting charge; this proved successful and was adopted the following year. As a buffer to prevent lead shot deforming, a resin was used as a packing material between the shot. A useful side effect of using the resin was that the combustion also gave a visual reference upon the shell bursting, as the resin shattered into a cloud of dust.