76 mm air defense gun M1938 (Russian: 76-мм зенитная пушка обр. 1938 г.) was 76.2 mm (3 inch) Soviet air defense gun, created by Soviet artillery designer M.N.Loginov. This gun was a modernized version of the 76.2 mm air defense gun model 1931, with a slightly modernized barrel and a completely new two-axle carriage ZU-8. This carriage was also used for the more powerful 85 mm 52-K air defense gun, developed in 1939.
The 85 mm gun was chosen for mass production by the Soviet authorities and tooling was switched from the 76.2 mm AD guns, to the 85 mm gun. As a result of this decision, the total number of M1938 AD guns, delivered to the Red Army, was relatively small. These guns were used in the first stages of the German-Soviet War and were gradually replaced by the more powerful 52-Ks. The muzzle velocity of the 6.5 kg (14.33 lb) projectile was 816 m/s (2,677 ft/s) and this allowed the shell to reach a 9,250 m (30,347 ft) maximum altitude.
The external appearance of the 76 mm and 85 mm AD guns is very close; the two types can be differentiated by their muzzle brake, the larger gun possessing the larger muzzle brake.