[1] Initially designated the T-160, the new gun was installed for combat testing on a number of F-86 Sabre aircraft under the "GunVal" program in late 1952, and used in action over Korea in early 1953.

Extensive work had to be done on the forcing cone, heat dissipation, cook-off prevention, link testing, and reinforcement, to raise the mean time between failures to 1-in-1000 rounds fired.

[6] Four arms manufacturers, three independent companies, and a university research department, were involved in getting the weapon working correctly.

The unit's report for May through July 1967 states "A low-level type of attack has been used on bunker lines with a good deal of success.

In situations where the enemy is using less than bunker-type cover, the 20mm coverage is so effective that it is quite reasonable to assume that those individuals who were in the area are either dead or severely wounded.

While a major leap forward in aircraft armament, all revolver cannon suffer from the effects of barrel wear, heat dissipation, and parts life.

[9] The M39 served as the basis for the T-75 autocannon developed by Taiwan (Republic of China), as a more-powerful partial replacement for the M2HB machine gun onboard naval vessels and the HMMWV tactical vehicle, with its latest use being within the XTR-101 and XTR-102 weapon stations.