It is kind of funny that the headline is "deadliest gunslingers", but in the intro they say, "Here are 10 of the most well-known" (not deadliest). I've always been amazed that Sam Bass got as much public attention as he did. He got really lucky with one train robbery, but was otherwise pretty much a failure. I guess people are impressed that he "died game", but he certainly got a lot of notoriety then and now.
There are a number of others on the list that weren't particularly deadly as "gunslingers" either, but I guess they are mostly well-known. I would agree with "Deacon" Jim Miller's inclusion, though.
CC Griff