This sleeve opened a series of gas ports which bled off exhaust gases and so determined the range.

The project was deemed overly complex and expensive, and was only produced for a short time, before being replaced by the Model 1939.

Despite the small number produced, some fell into German hands in 1941, who introduced them as the 5 cm Granatwerfer 205/1(r).

This mortar was without a tripod but instead relied on its barrel yoke which contained traverse and elevation adjustments.

The Finns were apparently not impressed with these Russian 50mm mortars, giving them mildly derogatory nicknames - "Naku" and "Tiltu", and not being over-zealous about re-issuing them.