I have seen Cowboy Action Shooters using black powder shells in their shotguns but I dont know if these by Navy Arms were what I saw being used. Many reloaded anyway. Lots of fun to watch the giant plumes of smoke from a black powder shoot!
As one of those cowboy shooters, virtually all of us reload. Last time I checked (several years ago) commercial black powder shotgun shells were at least a $1 per shell, not counting shipping, taxes and maybe the Hazmat fee. I've never seen the Navy Arms shells