Agent Carter, when attempting to recover zodiac, fires her PPK sixteen times without reloading. A PPK can hold either 9 or 10 rounds. Impossible to fire that many times without reloading.
The events portrayed in Marvel One-Shot: Agent Carter occurred one year after Captain America went into the ice, making it no later than 1946. There is a fallout shelter sign above the stairs to the SSR office where Agent Carter works, but the U.S. government created the design for the fallout shelter sign in 1961.