I have taken a cow elk with a std. cor-loct and it was a one shot kill.But that was only by luck! The bullet hit the shoulder and ricocheted into the neck. If the bullet had not gone into the neck killing the animal.....It would have been a long day.
I have no experience with the ultras.But I would practice with the Cor-Locts and hunt with a premium bullet (Partition,Accubond,Failsafe,etc)