.44 Rimfire is basically unobtanium today, it was last produced commercially in the 1920s or 1930s. Even single rounds are collectable. I recall reading about a Sioux or somebody who has a Henry and an ever dwindling cache of ammunition that has been handed down from father to son, father to son, from whomever captured it originally. Once every year or so they pop off a couple rounds or somesuch. Original Henry repeaters are expensive.
**it was last produced commercially in the 1920s or 1930s.***
I believe an ammo company ran off a bunch back in the 1980s. I remember seeing them advertised in one of the gun magazines.