Could easily have been the 7N6 rounds used as well, recently banned as being classified as armor piercing (AP).
Yeah, but they’re really just inexpensive military mild steel core, cheaper than lead core. The AP thing was just a pretext for banning an inexpensive ammo source. Real AP ammo is going to be depleted uranium or have a hardened tungsten carbide penetrator. Forgive my pedantry if you know this already, it’s just the “steel core = AP” thing is a pet peeve, so I never miss the opportunity to blather about it in case anyone not in the know reads this. :)