Vagabond,
TSX's are great bullet, but would like to comment on something in your post that's a common misconception. Retained weight is NOT the most important factor in penetration, everything being equal in a bullet. Frontal area is. If a bullet opens into a big, wide "mushroom" it won't penetrate nearly as deeply as a bullet that doesn't open up so widely.
One of the reasons TSX's (similar bullets such as the discontinued Combined Tectnology Fail Safe and Nosler E-Tip) penetrate so deeply is that even if they do open up to a certain diameter (and usually it's not all that wide, especially when compared to some bonded-core bullets) there are spaces in between the petals. This the big reason they penetrate so deeply. Retained weight is also important, but a secondary factor. I have seen bullets that retained 90-95% of their weight and didn't penetrate all that deeply, because they opened up so widely.
The fact is that there are indeed some bullets that will, for all practical purposes, penetrate just as deeply as a TSX, even though they lose some weight.
