I love wolf ammo for the AK, but at the indoor range I shoot yugo surplus (if I can find it).
The steel inner jacket in wolf may be bad for the backstop.
In reality, though, the steel case is the real safetly hazard.
The floor in all the indoor ranges I have been to is concrete. Steel cases bouncing off of concrete can generate sparks. I know, there is a sizeable fireball coming out of the muzzle, but it isn't on the floor.
Next time you are at an indoor range, while there is a cease fire or after the range shuts down, look in front of the benches at the floor. What you will see looks like dust, but is in fact unburned powder. I have swept this up before, and there is a sizable quantity after only a few hours of rifle shooting.
However unlikely, a steel case impacting the floor could cause a spark and ingite the powder. The resulting flash and subsequent burn would be bad for everyone.