Did some quick guesstimates and it could kill. It is still unlikely but it only takes a force of 60 ft. lbs. to start hitting potentially fatal numbers. A standard 30-06 round is 30 pounds of force when hitting within its terminal velocity and the muzzy round could have been twice as heavy (mass) than the -06 round. The mile and a half may be an exagerration. If so it may have had more speed/force than if it were just at terminal velocity speeds.
Crazy either way.