Plenty of people met their maker at the end of an 8" barrel and a .44 round ball going 800fps..... Surely a .410 can do the same... as a weapon against humans.
I am sure its lethal, but its weak compared to modern weapons.
Like I said, fine bird and squirrel gun with a proper stock, and maybe could be pressed into defense with a pocket full of slugs. But 5 rounds of slow loading weak ammo makes a piss poor weapon, and hacking the stock off this thing makes it only a weapon or toy.