If you stay at or below 100 gr of powder with deer sized game, you are probably fine with powerbelts. Shoot them with 105-150 gr of powder and you are asking for trouble. If shot too fast, they blow up and fragment, which may or may not put a deer down soon. That said, I once had a powerbelt pencil through an elk. Missed all the ribs, and went straight through. That was a flat nose though.

I switched to the Hornady FPB. They have a plastic tip up front to encourage expansion and have a lead alloy body to help it hold together. Have had good luck and good accuracy with them, and they are cheaper.