It's a step up over the older standard Core-Lokt, but I would not consider it a tough bullet like the Nosler partition or similar bullets. It would be a good bullet for deer and similar size animals, but I personally would not use it on elk unless I limited my shots to broadside lung hits.
I use 140's in my 270 for deer, does great, hits bone and mushrooms perfeftly. I also use the 180 grains in my 300 win mag for elk. Have killed two cows so far. One was about 250 yards, hit a couple ribs and went clear through her. I think there a great bullett.
It is a bonded bullet. You can compare it to Accubonds or Interbonds. The Ultra will hold together as well or better than the Partition. As a matter of fact, the Accubond was developed to act like a Partition while having an accuracy advantage. mtmuley