COTW says the .41 Long RF was used by the Colt New Line revolvers. "The Enterprise #4, Favorite #4, Forehand & Wadsworth, Webley, and other revolvers were available in this caliber. A few cheap single shot rifles also chambered it. It has been obsolete since the 1920s."

The .41 Short RF was used principally in various Derringers, such as the Remington Double Derringer.

COTW gives the case lengths of the .41 Short RF and .41 Long RF as .467" and .635" respectively. Both have case diameters of .406"-.407". I'd bet you have a box of .41 Long RF. Too bad you don't have the full cardboard box.