I made a video on how a 50cal bullet expands when it is shot subsonic in some milkjugs
needless to say, there was no expansion using powerbelt HP bullets.
here is the video in case someone wants to see it:
i ordered some pure lead powerbelts and will soon play with the Thompson Center Maxi-Hunter Bullets 50 Caliber 275 Grain Lead Hollow bullets to see how they do..