Versions of the M1977 gun were installed on main battle tanks (TR-77 and TR-85) and ship turrets on river monitors.

The A407 100mm anti-tank gun was the first artillery piece designed in Romania after World War II.

The first variant of the gun, the M1975 (M stands for Model) had a semi-automatic horizontal sliding wedge type breech lock.

The second variant, M1977, had a more practical vertical sliding wedge breech block.

[1] The M1977 can be also used as a field gun at brigade level, as it has a maximum range of 20.6 kilometers.