Interbonds on elk/deer...antelope????

[Mills]

I recently shot a cow elk with a 7mmSTW loaded with a 139 grn Hornady Interbond with a muzzle velocity of 3300 fps. I realize this probably wasn't the best bullet weight to use, but hang with me. She was on the move at about 200 yards and my bullet hit her broadside, slightly back and went through her liver (as I would later determine). She slowed up, dropped into a little creek bed and started walking. I couldn't get another shot at her. I tracked her down the creek bed to a semi frozen river which she crossed. I could not. After a two hour ordeal of getting back to my vehicle and driving to a bridge and back to her blood trail, I found her bedded in some timber and had to shoot her one more time.
Now, I've read the posts on this site where people are talking about massive damage to deer with the interbond bullet. Earlier in the year, I shot a nice whitetail buck with the same setup and it performed exceptionally. But on the elk, I experienced the contrary. I had a nickel size entry would and half dollar size exit wound. Like I said the liver was pierced by the bullet, but there was no real trauma to speak of. It's almost like the bullet barely opened up at all. Was my situation with the elk just a matter of too little bullet for too big an animal (she weighed 460lbs)?
Since then I've moved away from the magnum cartridge and switched to a .280 rem. Because of it's exceptional accuracy and performance on my last deer, I'd like to load the interbond again for deer and maybe an antelope...and an elk if I ever get the change again (will use the 154s if I do). My question is, is the interbond too sturdy to shoot at an antelope? Would it just pencil through with little expansion on such a small animal? Thanks.