The 87gr bullet is a direct result of them pushing to achieve the 3000fps milestone for a production cartridge with the 250-3000 Savage from a 24" barrel.
I looked at 25 Sharps, ran all the ballistics (3000fps with 87gr is from a 24" barrel), then looked at my 6.5 Grendel data, and realized it offered nothing other than use with existing AR15 bolt and normal AR15 magazines.
90gr TNT from Federal does 3000fps from 24" Grendel, and 2890-2905fps from 18" Grendel, with much lower working pressure.
I think the 25 Sharps would have made a nice .257 Bore Service Rifle Cartridge, but the case design suffers from limited ogive length constraints.
The 5.45x39 case or something similar would be a lot better as a starting point for optimum small bore in the AR15.
It will kill medium game all day long with the right bullet and shot placement through the vitals or CNS, no miracles there.
I wish the SPC case would have been chambered in a .257 bore, since .257 is the most neglected bore diameter with practical use for hunting and target.