I don't have a .338 RUM but I have used the TBBC and IMO they are, along with the Swift A-Frame, the absolute best bullet for terminal performance made today, including Barnes. They are not as stream lined as some of the others so they bleed off velocity a little faster than an accubond style bullet but their performance on game is outstanding.

What more could you ask for in a bullet? A bonded core bullet with a thick tapered jacked for excelent expansion over a wide range of velocity. A solid rear section for very high weight retention that also limits over expansion thus promoting penetration.

I recovered one under the off side skin of a cow elk and the mushroom was literally picture perfect, aside from the bone fragments and blood.

The TBBC and A-Frame are like a Nosler Partition on stearoids that keeps its front lead core in tact instead of shedding it at high impact velocity like a partition can do. The only down side is the price.