Remember that unlike most other service cartridges at this time, which had long since moved to spitzer bullets, the 6.5 Carcano still used the old-fashioned round nose jacketed bullet, the least effective type, perfectly designed to drill a neat, small hole. Combine this with being only .26 caliber, I wouldn't doubt it lacked stopping power by comparison.
Dig up some old reports on that round....it seemed to do something that most would not discover for another 30years....it tended to tumble, and really start to move around if it hit anything hard...like a bone.