levi - did you slip that slug between its ribs? If so, it wouldn't really matter what ammo or load you may have been using. Apparently the bullet did its job as the animal piled up quickly. You often get blood trails when you bust through ribs on the off-side leaving a lot of exit wound damage or if the bullet has upset while coarsing through the body and exits keyholed, leaving a much larger exit wound, and often an attendant blood trail.
One of our other forums has a thread about the same problem with the 6.5 Swede, so the problem may not be that uncommon. HTH. Mikey.