The weapon was able to penetrate 2 m (6 ft 7 in) of reinforced concrete with its special armour-piercing shell, which weighed 384 kg (847 lb).

In 1916, the M.11 design was upgraded and the new M.11/16 was produced - the difference was mainly that the firing platform had been modified to allow for a traverse of 360 degrees.

Eight Mörsers were loaned to the German Army and they were first fired in action on the Western Front at the start of World War I.

In 1915, ten howitzers were used in support of the Austro-Hungarian-German invasion of Serbia under the German General August von Mackensen.

In the period between the world wars, large numbers of mortars were in service in Yugoslavia (4 M.11 and 6 M.16), Romania, Italy (23 M.11, 16 M.11/16 and 16 M.16), Czechoslovakia (17 M.16) and Hungary (3 M.11 and 2 M.16).

In 1939, Germany seized all 17 pieces from Czechoslovakia and repaired the howitzer from the Arsenal Museum, designating them 30.5 cm Mörser (t).