The 45 mm D-24 was a minimal adaptation of an anti-tank gun that was created by taking the latter's barrel and mounting it on a simple pedestal mount. Its semi-automatic breech automatically ejected the cartridge case and locked open, ready for the next round. This was less than ideal for an anti-aircraft weapon that relied on its rate of fire to inflict damage on aircraft because every round had to be hand-loaded. Fully automatic weapons of roughly this caliber, like the 40 mm typically used 4-5 round clips of ammunition to produce rates of fire four times as high.

Early production guns had a built-up barrel, but later ones used a monobloc. There were problems with the breech mechanism early in the production run, and a number of the first year's production run lacked the semi-automatic breech entirely.