Largest bore size (calibre)

The world's largest bore for a piece of artillery measures 91 cm (36 in) in diameter and belongs to the Mallet mortar which was designed by Robert Mallet (Ireland) and completed in March 1857. It is currently on display at the Royal Armouries, Fort Nelson, Hampshire, UK. The mortar is one of only two ever built. They were made with the intention of being used to bombard the fortifications at Sebastopol from inland, during the Crimean War of 1864-56. However, they were not ready in time for combat and since then have never been fired in aggression. Amazingly, Robert Mallet designed the gun in reverse, determining the desired effect, then working backwards thinking of a projectile needed to produce that impact, and then a gun capable of launching the projectile. The chase (the main barrel of the gun, excluding the muzzle) is 203 cm (80 in) long and 91 cm (3 ft) at its widest diameter. The whole gun was built from separate components of forged and cast iron and weighs 42.6 tonnes (94,080 lb).