Saw a conversation about this in another site. Not much info from Hevi about specifications. Looks to be some partial tungsten/mystery alloy mix. Same weight as lead, lower tungsten weight, but not that hybrid 50/50 junker Hevi Metal.
Compared to Heavi Metal, Hevi X indeed from 20% to 35% in some mathematics of pellet count and knock down power.
@ 1450 fps on 1 1/4 oz shot, and the weight of lead, if can hold pattern and not bust apart, this could be a unicorn at $35 per 25 ct box.
Got me a coupon to Fleet Farm, maybe check this out.