Mike, I'm asking if the actual length of the physical sight got shorter on 1899 A.B, Cs at some point.
I'm sure there are sight-ologists with data here that can comment perhaps in more depth, but I'll take a stab at it.
The early "long rear rights" came in several types (2-3?) over the years. Rocky Mountain #14 comes to mind as one of them. Used on both 1895 & 1899 rifles.
Savage also offered other optional rear sights at the same time. Listed in early catalogs. Rocky Mountain (buckhorn) pat. 1911 comes to mind.
As mentioned earlier, the ~5 5/8" dovetail could accept long, short or other optional rear sights.
The dovetail closer to the rec'r ring ~ x x/x"?? could accept short or other optional rears sights, but not compatible with long rear sights.
So, was the long rear sight phased out or discontinued at some point as "standard" in favor of another rear sight as "standard"? Possibly, but identifying a date or serial number is likely a fuzzy area or range in time/S.N.
Just my observations. (it is Savage)