In 1951, the Federal Secretariat of People's Defense (Serbo-Croatian: Savezni sekretarijat za narodnu odbranu – SSNO) purchased the manufacturing licence of the single-barrel Hispano-Suiza HS.804 20mm L/70 anti-aircraft autocannon mounted on the HSS.630-3 towed gun carriage.

In addition, an engine of the same type as the M55 A3 B1 has been placed under the gunner's seat, which was moved from the lateral position found on the previous version in order to improve the weight distribution of the three barrels and prevent them from vibrating.

When the cannon is put into position, the towed carriage is removed, and a small splinter-proof shield has been installed in front of the targeting device and the gunner.

[4] The M55 A4 M1 was first introduced in 1983, and consists on a modified A4 B1 system upgraded with the Galileo J171 ballistic computer, mounted on a turret installed in the top roof of a BOV armoured personnel carrier.

The Zastava M55 was also employed by the People's Forces of Liberation of Mozambique (FPLM) during both the Mozambican Civil War (1977–1992) and the later phase of the Rhodesian Bush War, with a few guns falling into the hands of the Rhodesian Security Forces in the course of their covert cross-border raids on Zimbabwe African National Liberation Army (ZANLA) guerrilla training camps in Mozambique during the late 1970s.