The term “automatic” does not apply to semi-automatic firearms. It is a mistake to describe a semi-automatic firearm as an “automatic weapon”.

“Automatic weapons fire” refers to the steady series of reports or discharges of a fully-automatic firearm.

There have been archaic uses of the word “automatic” being used alone as a noun to refer to a semi-automatic handgun. This usage may have been chiefly British, and it fell out of use around the 1930s. Creative writers may find this appropriate for period dialog.