Although the M42 Duster was initially designed for an anti-aircraft role, it proved to be effective against unarmored ground forces in the Vietnam War, primarily against standard Infantry.

The 40 mm guns were initially planned to be aimed with the assistance of a radar fire control system housed in a secondary vehicle of similar design but this idea was scrapped as development costs mounted.

Sometime in the late 50s, the U.S. Army reached the conclusion that anti-aircraft guns were no longer viable in the jet age and began fielding a self-propelled version of the HAWK SAM instead.

Accordingly, the M42 was retired from front line service and passed to the National Guard with the last M42s leaving the regular Army by 1963, except for the 4th Battalion, 517th Air Defense Artillery Regiment in the Panama Canal Zone, which operated two batteries of M42s into the 1970s.

To ensure some low altitude anti-aircraft capability for the ever-increasing amount of forces fielded in South Vietnam, the Army began recalling M42A1s back into active service and organizing them into air defense artillery (ADA) battalions.

According to an article that appeared in Vietnam Magazine: M-55s and M-42s were old pieces of equipment that needed a lot of maintenance and required hard-to-get spare parts.

Thus, despite its cross country capability, it was not wise to use the Duster in extended search and destroy operations in heavy jungle terrain because of excessive wear on engines, transmissions, and suspensions.

Better yet, the Duster's high ground clearance and excellent suspension-system design gave it an ability to withstand land mine explosions with minimal crew casualties.

Quads beefed up the defenses of remote fire bases, while Dusters accompanied both supply and tactical convoys along contested highways to break up ambushes.

Dusters of Battery C, 1-44th Artillery, led the task force of Operations Pegasus that broke the siege of Khe Sanh in April 1968.

Dusters and Quads provided critical final-protective fires throughout Vietnam during the Tet offensive and later took part in Operation Lam Son 719.

A self-propelled M42A1 Duster unit, the 1-44th supported the Marines at places like Con Thien and Khe Sanh Combat Base as well as Army divisions in South Vietnam's rugged I Corps region.

Members of these units not only covered the entire Central Highlands, but also supported firebases and operations along the DMZ to the north and Saigon to the south.

The Duster and Quads largely operated in pairs at firebases, strong points, and in support of engineers building roads and transportation groups protecting convoys.