Randy, I had a question about the same back in 2005, so I decided to see for myself what a 168 TSX looked like at 300 yards fired into wet, bundled phone books. I set up my chronograph at 300 yards and shot through the sky-screen clocking velocity. The bullet was fired at 2,880 fps from my 30-06. I've lost my notes, but I remember the clock measured right at 2,000 fps or just a bit less at the 300 yard mark.
On the left is the 168 TSX I caught in the phone book at 300 yards, on the right is a 168 TSX I caught at 50 yards in a bull elk later that fall:
There's nothing especially "wrong" with the TSX/TTSX, but as John pointed out, at 30-06 velocities I think there are better bullets for use out to 425 yards.