Pete, I have enlarged and sharpened the pixels a little.
The gun is of typical military origin and is serial numbered in that pattern... the word under the safety is definitely GESICHERT.
I don't see the Mauser hump so it is probably made prior to the 40's
I can make out "LUGER" as the large word engraved on the BOTTOM left flat of the grip frame.
There are three smaller words above it.
Squinting, it appears that the last word of the three is "Parabellum"
So I will venture a couple of guesses.
"AN AMERICAN PARABELLUM"
or
"THE AMERICAN HANDGUNNER"
How about anyone else taking a guess... This is the best I could do witht he gif file you posted.
