That's interesting, but wheter or not they are bonded I guess doesn't matter to me considering every test I've don't with the Gold Dot has indicated they don't separate. I tested 3 different bullets recently in a box lined with a plastic trash bag, and the box filled with water and rolled up denim jeans packed into it. The XTPs did very well and the Gold Dots as well. But the 3rd bullet, a Sierra HP, exploded into pieces . I did this testing with each bullet multiple times with the same simular results with .357 125 grain bullets. Expansion with both the XTPs and Gold Dots was nearly identical. And both of those penetrated all the way through and stopped against the soft sand embankment.
Regarding the Hot Core, I killed an elk with a .270 Hot Core 130 grain BT and the onyl shot I had was from the rear. The bullet entered just above the poop shoot and traveled the entire spinal colum through every single vertebra and came to rest at the base of the neck. When I remove the bullet it was in a very controlled expanded shape, and weight retention after washing away the bone material was 89%. Good enough for me, considering this last fall my Son's and I used the standard Speer, not the Hot Core, and the bullet fragmented into pieces after only going though a shoulder of a mule deer, three mule deer with the same results. The Hot Cores have always performed without failing like that on every animal I've shot with them. I'll stick to Speer Hot Core or Barnes solids because of proven sucess.