I can't tell you the technical difference between eld-x and sst but I've hunted and killed deer with both in 6.5 Creedmoor.

I didn't care for the results on the sst's. Killed two bucks with the sst's. Both were less than 100 yds when shot and both were dead within 40 yards. Neither bled a drop. In my opinion the bullet expanded/ frangmented too quickly at that range and didn't exit, thus no blood. On one deer no problem because he never left my sight. The other one ran into a briar thicket. Had to walk circles to find him which was not fun.

I've had better results with the eld-x at longer and shorter ranges. Good pass throughs with expansion. Dead deer with blood trail if needed. I'm sticking with eld-x again this year.

I've hunted with Barnes tsx in a 300 mag with good results. I would hesitate to hunt with it either.