Yeah, meant to tell you that mild steel will get hammered with high velocity jacketed ammo. You'll find that your .223 will do just as much , sometimes more damage.
Proper Silhouette targets are made from BISALLOY, can't remember what grade, ( you there Strikey? ) it can stand up to repeated use no matter what you throw at it. Although I reckon Brett1868 would have something that would destroy even that stuff.
It's horribly expensive compared to mild steel.
The DY-MARK paint is what we usually use for competition for the reasons given, I do still reckon white primer, especially on bare steel has the edge on it.
If you love the sound of smacking bullets into steel, have a go at Metallic Silhouette. Not only do you get the sound, but you also get the visual of your target taking a tumble. Nailing rams at 500m and watching them fall is very satisfying.
Sending a 200m chicken cartwheeling through the air can be very entertaining.
We shoot 11 different classes from air rifle through to big bore black-powder cartridge. There are four targets, chicken, pig, turkey and ram. A match is 40 shots, 10 of each animal. They are all free-standing on stands and to score you have to knock them off. They are scaled for the various classes and distances.
Targets for Air-rifle are at 20,30,36 & 45 yards. Rimfire ( .22L.R only) are at 40, 60, 77 & 100m. Centrefire( minimum 6mm/.243 ) are at 200,300, 385 and 500m. All are shot off-hand unsupported ( no slings) using scoped rifles. There are 2 classes in rimfire and centrefire, open and hunter. Open is where you'll get fancy custom rifles up to 4.6 kg and hunter must be a standard, out of the box rifle not exceeding 4.2kg for c/fire and 3.86 for r/fire with minimum 2lb trigger. You can use your hunter rifle in open class, many people do. It 'aint easy, but it can be a very rewarding challenge.
Then there is Lever-action Rifle in small-bore, pistol calibre and rifle class. You shoot half-sized targets at 40,50 75 & 100m in small-bore ( .22 rimfire ) and pistol caliber and full-size targets at 50,100,150 & 200m in rifle class. Again shot off-hand but using open sights only, barrel, receiver or tang mounted. These matches are a lot cheaper to get into and very popular as you tend to hit a lot more targets as they are a lot bigger than the scoped rifle ones.. A $400 30/30 gives you as much chance as the next man/woman.
We also shoot BPCR, fullbore and .22 and Service Rifle matches although these are less regular.
Always looking for new shooters, so look up the nearest SSAA club that shoots it and have a go.