Another thought worth pointing out, before responding to your recent post:
Steel plates are targets - targets are consumable. They'll last for years and years, but they don't last forever, and comparatively, they don't really NEED to last forever to be cost effective. Buying a $40-60 10" round target and pocking it up on one side for a few thousand rounds, then turning it over and pocking up the other side for a few thousand rounds before you have to replace it still ends up FAR cheaper than any paper targets would have been for the same volume of shooting. Let alone the advantage of instant feedback for the shooter on target - it's a very different game.
Anyone actually shoot frangibles? Rmr has them priced low enough to make them worth it if i can get closer to steel without damaging the steel or myself.
How close are you wanting to get? Your original post says "50yrds or so," and as I mentioned, I've been shooting 50yrds with 223rems for years (shot some last evening, in fact). I haven't used branded "frangible" bullets, but rather with lightly constructed expanding bullets.
You do not need a special bullet to be able to shoot 50yrds on steel. Just don't use FMJ's or mono-metals at that range.
The RMR Frangible bullets are a 90/10 Copper/Tin alloy, and by name "Sinterfire" they're a thermo-compression formed bullet - This makes them brittle, but also giving them potential to be quite hard compared to a common cup and core or tipped expander. Take a shot on them, they're cheap enough - if it doesn't work and you pock the heck out of your plate, just turn it around; lesson learned. I might expect less perpendicular spall and maybe a bit more bounce back, but if you have your down angle on your plates as you should, that spatter will be directed down instead of back at the shooter.
The plates i have are used for rifle and pistol and i dont want to screw them up
There really isn't a metal suitable for super close rifle shooting of high velocity rounds, but shooting expanders out of a 16" AR at 50yrds isn't going to tear up the plates too bad, too quickly.
Another option, which I tend to favor most of the time - get bigger targets. A 24" gong at 50yrds is the same subtension as a 12" at 25yrds. It's more expensive, but they last longer, or a 12" gong at 75yrds is the same as an 8" at 50yrds or 4" at 25yrds... Etc etc... As long as you can process it mentally, and you space your targets appropriately to be relevant and relative to your shorter reference range, it feels and looks the same once you're over the sights, no matter how different it looks standing at the line before the beep.
Also, don't get too distracted by IPSC/IDPA torso targets. I've known a lot of guys who have ran out and bought them, since it just seems to make sense, BUT, unless you're competing and need that profile, they're REALLY over priced for the size. A ~12" x 20" target SEEMS large, but for a rifle, it's really no larger for a rifleman than a 12" circle, which costs about 1/2-2/3 as much.
Maybe i will get a few hundred next order just to see how they do
Might as well try some. Just make sure you have down angle on your plate hangers, it'll work itself out one way or the other after a few shots.