I have a 10" round plate from Arntzen Targets
. It's 3/8" AR500 steel. It's $35 + shipping. Best firearm accessory I ever purchased. I've put 1000's of rounds on it with my Mini-14, plus misc pistol calibers, and it's holding up nicely. Just don't shoot it with steel core bullets and it will last you a lifetime. I usually shoot it at 100 yards, closer for handgun use. I discovered that a 4 ft "shepherds hook" plant hanger works perfectly for hanging the plate, which has a hole at the top. I get mine from the garden center at Home Depot for like $6. While you're there pick up orange marker spray paint for adding good visibility to the plate.
I also have one of the new Caldwell spring loader popper targets which is AR550 steel. It's a bit pricey but a lot of fun as well. 79573 - Caldwell Magnum Resetting Popper Target AR-550 Steel Free Standing Frame
Yeah after awhile shooting paper gets kind of boring. Shooting reactive steel is great fun. You get instant feedback. I'm still amazed how violently a little 55 grain .223 bullet knocks around a 10 lbs steel plate at 100 yards!
*This post is not intended to diagnose, treat, cure, or prevent any disease.