I've had different plates from shootingtargets7.com for a couple years now. Held up perfectly. The gong target is tons of fun for pistols up close or long range rifle shooting.

Also got a pair of these 2/3rd size IPSC targets off amazon for about $50 each. Keep an eye on them, they go on sale every so often for $10 off: amazon.com/Titan-Silhouette-Shooting-Target-Single/dp/B073WMG739/ref=sr_1_10?dchild=1&keywords=titan+target&qid=1616312104&sr=8-10

Stick with AR500. I'd recommend 3/8" steel for most uses. If it's 22LR and 9mm or long range (500 yards +) then 1/4" can work. Thinner steel will sound better at long range if it's mounted loose enough that it can reverberate.

Remember - velocity of greater than ~2800 fps upon impact will cause AR500 steel to pit. It's not a matter of steel thickness, caliber, bullet weight, or energy; it's how quickly fast rounds impart thermal stress to the steel that causes the pitting. Higher energy rounds will cause thinner steel to bend, but it's the velocity that causes the pitting.

55 and 62 grain 5.56 kills AR500 steel inside of ~100 yards. Some weaker steel cased 62gr ammo is slow enough. 77gr ammo is gtg out of 16" barrels though. You can also hand load lighter bullets at lower velocity that work as well.