Russian ammo manufacturers are taking advantage of US ammo manufacturers reluctance to expand and they are coming into the mainstream market. Here is one of the Russian offerings for shotgun only states and CA. The slugs are made of steel and expand much quicker than our top of the line sabots. I do have questions about accuracy and range. The Russian idea of accuracy and mine often are widely different. This slug is made by Ddupleks.
There are several videos on this page. One is a ballistic clay test. Another is pig that is gut shot but he still drops instantly. Really the gut shot doesn't impress me that much. An adequate hunting rifle or just a plain old rifled slug will do the same thing with shock instead of splintering.
I have seen bear in NC that weighed 350 to 400 lb. The bear that the Russians drop instantly is much larger than any bear I have seen.
This slug is also a player in the police and home defense market. Since it splinters over penetration is not an issue. But it may lack the barrier destruction abilities that police demand from shotgun slugs.