While a 160-grain TSX in the right place would no doubt kill an elk, some years ago (long before the present how-light-can-we-go phase) my old friend Dave Gentry went up to British Columbia to kill a Shiras bull moose, because he was weary of waiting to draw a Montana tag. Dave was one of the early big fans of the X, and he chose for this trip the 175-grain X out of a .338 Winchester Magnum. The shot he eventually got was with a bull quartering away, and after it was all over his conclusion was that even with an X-Bullet, shooting a Shiras moose would have been better done with a heavier bullet. A typical Shiras bull isn't any larger than a big bull elk, and some aren't as large.
My experience with X's is that they'll penetrate about as deeply as a Nosler Partition weighing maybe 15-20% more. This of course depends on the particular Partition, as some of the bigger ones are designed to retain 85-90% of their weight, and hence penetrate just about as deeply as an X of the same weight and diameter. So I would doubt that the 160 TSX would penetrate as deeply as a 210 Partition. Now the 185 .338 TSX very well might, but not the 160.
Personally I'd go with a little more bullet than the 160 in the .338 Federal.
