The 25 cm schwerer Minenwerfer was a muzzle-loading, rifled mortar that had a hydro-spring type recoil system.

Shells filled with these substitutes nonetheless were the cause of many premature detonations, making the Minenwerfer riskier for the gun crew than normal artillery pieces.

The wheels were removed and the sMW was then placed in a pit or trench at least 1.5 meters (4 ft 11 in) deep, protecting the mortar and its crew.

Despite the extremely short range, the sMW proved to be potent as its massive shells were almost as effective in penetrating fortifications as the largest siege guns in the German inventory, including the 42 centimeters (17 in) Dicke Bertha (Big Bertha), a howitzer that was more than 50 times the weight of the sMW.

[1] A middle variant, which consisted of simply adding a 500mm barrel extension to existing a/A mortars, was the 25 cm schwerer Minenwerfer 16a.