Well, we have three steel target threads now. It seems to me that we have two kinds of less than optimum groups of opinion here.
The first group thinks that any metal should be shot and is always looking for a piece of "steel" to shoot. Well, there are thousands of kinds of steel. If it is not flat(wheel rim) or if it holes or craters when shot it is unsafe steel. Pock marked or dished plates that started life as suitable targets are not safe. If it is not hardfaced AR steel, don't shoot it!!!
The second group, possibly due to exposure to the first group, thinks all steel is unsafe. Again, flat, non-pocked steel suitable for caliber is safe. You don't have to do elaborate things angling the target. Non-fixed plates will fall, poppers will send a spent bullet off relative to their direction of fall. Some prefer forward falling poppers because they think they put bullets into the dirt better. In truth a forward faller moves back before forward, it still usually kicks the bullet up. Doesn't really matter, they don't come back. I've shot plates with 5.56 10 yards away, it really doesn't matter. Small fragments may come back, wear your glasses. I may equal R, but a whole bullet will not come back off of flat steel unless you can get a plate that does not move at all and a bullet that does not deform at all. I do not know anyone shooting hardened round steel balls, so that is not a concern. The guy with the .50 ricochet was undoubtedly shooting something that shouldn't have been shot.
The best bullets I've used for steel are plated bullets, mainly because they are dead soft lead. I believe they hit falling steel harder than a comparable FMJ because they spend most of their energy in contact with the steel. You can often find a plated bullet several yards away from the plate, fully flattened. If you see a FMJ kick up 50 feet in the air that means it still has energy that it didn't impart to the plate. The worst offenders for sending fragments back are JHP with jacket pieces and hardcast with lead splinters. Again, both usually occur with steel that is pocked up.
So, shoot good steel in a safe manner. Wear your glasses. If you get hit by a piece of jacket, you did not get shot, so no reason to whine on the internet. I've seen more dangerous crap come back from rocks in the berm. Anytime you shoot, unless you habitually shoot 4 ft of jello, assume something may come back your way and act accordingly.