Known as the grip or butt.
Pistol whipped
Look on the butt
you put the magazine into the butt of the pistol, then to charge the pistol pull the slide to the rear and let go or push down on the slide catch if there are no more rounds in the magazine.
The butt
Look on the butt of the revolver.
It's the very back end of a rifle or the bottom of the grip on a pistol.
Check the frame, barrel, butt and under the grips
Normally stamped on the left side of the frame for autos, and on the butt for revolvers.
No way to answer without detailed information on all markings and features.
SN's were not required at that time. If it has one, look on the butt or frame.
There is on mine, under the brass buttplate, on the left side. Mine is stamped 18, I believe.