152 mm mortar M1931 (NM) (Russian: 152-мм мортира образца 1931 года (НМ)) was a 152.4 mm (6 inch) artillery piece originally developed by the German arms
guns), equipped with the D-1 along with various other 152 mm howitzers, 122mmgunM1931/37 (A-19), 152 mm howitzer-gun M1937 (ML-20) or 107 mmgun M1910/30