Please reference the attached photographs depicting a grouping of three Triple Lock revolvers, all are nickel, and each of the most common barrel lengths are depicted: 6 1/2", 5", and 4". Nickel photographs poorly, and the 4" revolver has been completely refinished in amateur fashion. But, nonetheless, despite condition issues, you just don't see this every day.
FWIW, I believe only one or two nickel Triple Lock Target Models with a 7 1/2" barrel were produced, not sure how many that are non Target Models might have been produced in that barrel length. Not sure if, someday, this grouping could expand to four?