In my experience powerbelts are not great bullets. I lost a bull after 60 yd shot. ( i know you are asking about deer, specifically...) The next day I shot this buck at 40 yds. I shot as his front leg was fully extended so I did not hit shoulder. The entry hole is huge= bullet splattered/expanded/fragmented at the close shot. I recovered the buck but there was no exit and bullet fragments were all I found inside. I was using a Platinum Aero something Powerbelt... can't remember the specific bullet name. I think it was 350 gr weight.
If you want to bang your head against a wall to convince yourself they are adequate bullets, you can. And if distance , velocity and shot placement are ideal they will kill deer. But there are way better bullets out there. I switched to Federal bor loc lead bullets and have been very happy. I will always advise against powerbelts - leave them alone before you lose an animal to them. Listen to others' experience before you have to learn this lesson the hard way.