Gas check, 6.3 inch Rifled Muzzle Loading (RML) Howitzer, Mark I of 18 cwt, 1878-1880

Copper disc with raised rim with 20 rifling grooves, 1878-1880.

Gas checks like these were used on larger types of Victorian muzzle loading artillery pieces. They were placed at the base of the shell, after the black powder charge had been inserted into the gun. On firing the disc would expand and engage in the rifling grooves of the howitzer, imparting a spin onto the projectile. This would significantly increase the range and accuracy of the projectile.

Howitzers of this calibre were used by the Royal Artillery either in fixed fortifications, or as semi-mobile artillery. The howitzer had a range of around 3,700 metres.