This Collath bolt action rifle was built on an early, pre-1901, military rifle action made by Spandau arsenal. Collath had very good relations to the nearby Spandau arsenal. Perhaps he obtained a surplused early test action.
The varying standard powder charges reflect the advancements in powder and case technology from 1888 to 1910. Both the "Gewehrblättchenpulver" = (military-) rifle flake powder as well as the inside design of the brass case underwent some changes. Though all the military as well as most civilian loads of the cartridge M88 aka 8x57I were loaded with the same .318", 14.7g = 227gr round nose bullets, the other components changed slightly. Take, for example, the military loads: Originally the case was made of very thin brass and contained 2.75g = 42.4gr powder. When Maxim machineguns were tested in 1892, the thin cases were insufficient for mg use. A new case with heavier walls and so reduced powder space was developed for MG use in 1893, this contained 2.45g = 38gr powder. In 1901 a new case and load, the "Einheitshülse" = universal case for use in both rifles and machineguns was settled on, containing 2.67gr = 41gr and was introduced as the regulation charge. Judging from contemporary catalogs, by 1910 the standard commercial 8x57I load featured the same 14.7g bullet weight and was loaded with 2.45g T1910 powder for 650 m/s = 2133 fps. Apparently the Collath rifle was at first stamped for the 1901 military load. This was then corrected to the standard sporting load, as no "2.67g" load was available to civilians. This doesn't matter anyhow: As the CROWN-crown/N proofmarks show, it was proofed using the "4000 at Beschusspatrone" = proof cartridge.
BTW, the M88 action is neither weaker nor stronger than the Mannlicher-Schoenauer one, as it shares the same dimensions of receiver and bolt. The weak part of the military rifles and carbines was the thin barrel, covered by a sheet metal sleeve and prone to rust pitting at the already weak chamber area.