I have a gong, it's called a "beast rifle gong" I think the guy stopped making them, but you can find them if you google that. It took a LONG time to ship, but is very cool. it is made out of armor car plate and is about 2' by 3' and hangs from chains in a metal stand. When it is hit by a bullet it makes BOING! sound and you can tell you hit it, plus it moves from the impact of the bullet.
I have also used other metal targets suspended from wires, thought it takes some experimenting to find ones that will last (we didn't know anything about metal, just bought junk from the junk hard and experimented) We had one piece of metal of an old tractor that was almost as tough as the beast rifle gong.
The beast rifle gong is REALLY tough. I have fired thousands of rounds of pistol ammo and .223, 7.62x39 and 308 at it and it looks fine. I banged it with 7mm rem mag also. Great stuff. I looked into having a run of them made, but with steel prices up I don't think I could have them made cheap enough that I could even break even on them.
They are WAY more fun to shoot than paper. The only downside is they are kind of big so you don't exactly have to be careful about your shooting form and trigger control to hit them. I got pretty sloppy in my shooting after about a year of mostly shooting gongs v. mostly shooting paper targets.