I hunted with some guys several years ago that used the 270 and 280 with 140 partitions and they had no problems getting their bulls.
I would however use a better bullet, I've seen a couple bulls soak up lead and the 150 HDYs are rather soft. I load that bullet for a few 270s for deer and they often fail to exit on small whitetails. Usually mushroomed on the off side. I would be learly of shooting a bull with them unless it was a perfect rib/lung/rib presentation, but those just don't always happen. I can see the HDy failing on a shoulder impact very easily. Go with a Aframe, Partition, NAB, or Scir and be done with the worry.
Good Luck
Reloader
