I'll start with the Model 1899 4" targets, one in blue and the other in nickel. They both letter, as shown below.
The next set of pictures are the 1899 8" targets, and they do measure as 8.0" . The blue one is all original, and was shipped to Dr Reginald Sayre, who was Captain of several US Olympic teams.
There is probably, but not for sure, one other all-original 8" 1899 that would have belonged to Charles Axtell, a well known shooter and US Olympic team member.
There is one other known not-original 8", serial 014, that was shipped to DB Wesson as a 6 1/2" gun. A second entry in the 0 book shows it as a 8" revolver in 1906, belonging to Charley Call.
The nickel 8", shown in the pictures with the Sayre's blue gun, is of unknown original barrel length. It's factory letter, and communications with Roy, show that no information is available as to it's shipping configuration. When I acquired it, years ago, it had a replacement barrel with a broken forcing cone. Jim Fisher kindly let me have an original 8" nickel 1899 barrel, which is what is on the gun now.
Regards, Mike Priwer