...i have difficulty getting good rolls out of heavy metal dice: they kind of plop down with a thud and just. STOP.
...that and they're terribly hard on whatever rolling surface i use; towers seem to be the only way to get a reasonably random roll from them and those grow beaten-up by heavy metal dice in pretty short order...
...i wonder if the more-rounded edges roll any better?..i have one hydro74 licensed set similar to those pictured here; i should compare them to my sharper-edged ultrapro heavy metal dice...