Im not sure but if that rifle was made in 1886 it should be black powder only. Im not gonna say for that the Western cartridges arent black powder but I do believe that western came out after smokeless came out. I dont think I would shoot them in that gun at all. Im thinking also that if its a jacketed slug that would make it after smokeless powder to. My advice would be not shooting it and go out and but some black powder rounds. Maybe somebody else can chime in and let me know if Im right. You can check buffalo arms for ammoor black dawg ammo for 45-70 ammo.