I’ve used the similar Nosler BT bullet for deer for over 10 years now in my 243 with absolutely lights out results. They produce devastating shock and, essentially, they do exactly what Nosler and Hornady say they do. That is they transfer the maximum amount of shock with immediate expansion on contact.
My observations from personally shooting deer with these bullets is that in a high velocity round, the shock transfer is so great it’s like the deer is hit by lightning. There’s no blood trail to follow because the deer drop in their tracks. I have personally taken 4 deer and others have used my rifle to take 3 more and none of them has gotten farther than 30 yards, and 6 of the 7 literally crumpled in their tracks.
I think some misunderstand these bullets, they see the ballistic tip which is similar to a varmint bullet and that leads them to conclude that these bullets “explode” on impact, which is not the case.
I think the sweet spot for the SST and BT is deer/antelope-sized game with sub-26 bore cartridges that drive bullets fast. That produces the shock that really makes these bullets shine. I would not hesitate to shoot an SST out of a 257 roberts.