A man-portable infantry mortar in the pattern of the Stokes Mortar, the RM-40 was designed to use gas venting instead of angle of fire to control range; while this gave the advantage of being able to fire through tighter apertures, it also introduced greater mechanical complexity to the mortar, and was abandoned in later models. The main tube is fitted with a gas restriction collar at the base and a leather handgrip just below the folding bipod. The bipod is fitted with a shock absorber assembly, adjustments for traversing the mortar and leveling the legs, and a mounting point for a sight (not included), and marked "1940". The baseplate is spiked on the bottom.

Fine, with 70% of the reapplied green paint finish, showing areas of uneven application, flaking and wear. Both the bipod and the gas regulation mechanism are in fine order. NOTE: This Destructive Device is a National Firearms Act (NFA), fully transferable Class 3, which is registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives, (BATFE) under the provisions of 18 U.S.C. Chapter 44 and 27 CFR part 479, National Firearms Act.