Benbo,
My wife had a somewhat similar meat-loss experience with the 100 TTSX at 3150 fps from her NULA .257 Roberts--though the deer didn't die all that fast. She shot a mature mule deer buck at 100 yards just behind the shoulder, as he stood broadside. He made a tiny jump, then started walking off almost as if he hadn't been hit--though we heard the bullet hit, and she was shooting from prone. He slowed, and then stopped after about 100 yards. She was about to shoot again when he collapsed.
The bullet had landed right where she aimed, in the pocket behind the shoulder, about 1/3 of the way up from the bottom of the chest--but there was considerable meat damage, more than we'd ever seen from any monolithic, even though the bullet didn't hit bone.
Killed my first big game animal with a Barnes X around 30 years ago, and Eileen started using them when the TSX appeared in 2003. (In fact she was the first person to provide Coni Brooks with a field-report about using the TSX on a bull elk.) Between us have taken over 100 animals with Barnes monos, including the original X-Bullet, including the blue-coated version, TSX, Tipped TSX and LRX. Our experience with the TSX is the same as yours, that they don't tend to kill as fast as the TTSX (Eileen's mule deer buck was the biggest exception to that), and we've even had a couple fail to expand.
And I did find the TSXs didn't kill as well when not driven pretty fast. One animal in particular was a bull kudu I killed in South Africa with a 160-grain TSX started at around 2700 fps from a 7x57. He was about 250 yards away, and I was sitting with the rifle resting on sticks. The bullet went right where I aimed, just behind the shoulder about 1/3 of the way up from the bottom of the chest, and the kudu jumped a little and trotted into a patch of nearby brush before I could shoot again, where it disappeared.
I headed over there, ready to shoot again if he jumped, and got within maybe 75 yards before I could see him, lying down with his head up behind a screen of brush. I tried to pick a path through the brush, but the bullet deflected and never hit him, and was about to try again when his head started slowly dropping and he rolled over on his side. That was at least a couple minutes after the initial shot, which had gone where I'd aimed--but it didn't expand much, if at all, leaving a very narrow wound channel through the lungs above the heart--which is why we prefer the TTSXs or LRXs in calibers from .30 on down.
On the other hand, TSXs above .30 caliber have a MUCH larger hollow-point than the smaller-caliber models, and expand well even at modest muzzle velocities.
