Wayne,
Not trying to start an argument but years ago, when I was seriously studying this stuff, I read an actual news paper account of Hickok doing this. Even into the 1870s he was still carrying and using two '51 Navy Colts. And as most did with the cap-n-ball guns all six chambers were loaded. The hammer rested on a safety notch between the nipples.
Even when cartridge guns became more the norm (Colt's Single Action Army and Frontier Six Shooter being prime examples) a lot of people still carried them loaded with six, resting the hammer on the "safety notch", the first click as you pulled it back. Wyatt Earp was known to have had his Colt revolver, so loaded, fall out of his holster while he was setting in a saloon in Kansas. It landed on the hammer and went off when the safety notch broke the sear part of the trigger. It was reported in the towns paper and policeman Earp was the brunt of considerable teasing for a while.
I also read an interview with an old guy who served as a Texas Ranger as a young man, right after the turn of the Century along the Rio Grande. When the interviewer asked if they loaded five and kept the hammer down on the empty chamber the ol' boy laughed at him. He said they always loaded six, but it you were afraid go ahead and load just five.
It was indeed a different time.
Dave