Ron,
Your spot on. Hydraulic pressure is the problem im having with the new bullets. I don't remember if I sent you any of the new Lehigh bullets. But the slits in the new bullets are not allowing the hydraulic pressure to build like the bloodlines do. So when those petals shear they don't have the explosion effect like the Bloodlines. Dave figured this out and is working on making them better when he gets a chance for me. These bullets still kill game, but I put them into a category of a mushrooming bullet. I thought at first the petals weren't shearing, but after some tests similar to yours they are shearing with no problem.