Accubonds are great for antelope and I doubt that they just blew right through the antelope without expanding. Antelope are a lot tougher than many folks give them credit for and it would not surprise me in the least that you had to shoot this one three times although from the sounds of it the antelope should have been dead on it's feet after the second shot. I've shot a lot of critters with the Accubond and the performance has been just perfect. Nice expansion and usually exit holes.
I have shot them into water jugs as another way to test and evaluate them for expansion, penetration, and weight retention and from 25 - 500 yards they just work and work very well. I had a buddy shoot an antelope with his 45-70 at about 200 yards. Hit it perfectly behind the shoulder in the lungs and it never even acted like it was hit after absorbing that big old bullet. The buck ran about 100 yards before it dropped. My father shot an antelope with his 7mm Remington and 160 gr. Nosler Partition in the neck. This was a medium size doe. He missed the spine and got the main artery. This little doe ran about 400 yards before she fell!
I would continue to use the Accubond with confidence.