This month's item is known by several names, including reloader, shell capper, and primer capper. It's used to insert the primer cap into the brass casing of a shotgun shell. Recappers are used by individuals who, for one reason or another, reload their own shells. Of course, they're available in various sizes. These tools have been around a long time. We  found a similar one patented in 1881 and an "improved" version patented years earlier, in 1877.

This pic shows how the tool is used. The shell is placed in the hole, allowing the user to affix a primer cap to the top of the shell. When the handle is depressed, the protrusion on the opposite handle presses the cap into place. Reloading shell cartridges entails several steps, including replacing the used primer, reshaping the shell, inserting powder, wads, and shot, and crimping the end of the shell to retain the material inside. For that reason, many tools include a recapping function as part of a multi-purpose tool. To
enlarge the pic shown, click here.