I started using the original Barnes X in my 270win 25 years ago. I use it now in everything from my.223 up to 300wsm. I have taken everything from predators and hogs with the 223, deer and multiple elk with the 270, and kudu, gemsbok, impala, and blue wildebeest with the 300. Its a great bullet and very accurate out of every gun I have tried it through.
I had one "failure" on my kudu from the 300wsm. I posted it on the Bullet Performance Database thread here on AH. Failure is in " " because it was still a one shot kill with no tracking involved. It was due to a bad angle hitting bone and closing off the cavity preventing expansion.
Left bullet recovered from kudu. Right bullet recovered from 90 yard shot on blue wildebeest. That is the way all of mine have looked that I recovered except the one pictured here.