By Golly, I found it! Havilah Babcock's "Fallen Lady" debuted in Field and Stream magazine in the May, 1962 issue (volume LXIX No. 1) on page 68, illustrated by Tom Rost with just the scene I thought I remembered. Last I saw that page I would have been 14 years old and probably a freshman in High school.

And the gun in question was a Parker!...Geo

"My find was an ancient Parker double, and I remembered that I'd once called her Fallen Lady."