Just want to give a shout out to a fine company of veterans who make some mighty fine AR500 metal targets;

http://shootingtargets7.com/store/

I have delt with these folks, buying some of their 3/8 & 1/2 inch AR500 gongs, and they hold up very well from all the ranges I've tested a 3/8" thick one from with one of my .45 patch-n-ball rifle's and a 65 grain load of 3fg.  Ranges I've tested so far have been - 30, 40, 50, 60, 70, and 80 yards on an 8" x 3/8" gong.  It makes a nice ringing noise when hit as well, so if your not certain you hit the target, the ring will let you know (though I've not ran into this problem as yet).

Our club has been looking for good AR500 gong targets that don't cost a fortune, and these are the ones.  Good prices, good targets, they should last a lifetime especially using the soft lead round ball.  I have no doubts they would hold up equally as well to conicals.  Did I mention good prices and made by veterans!