It depends on the thickness of the metal, but bigger is not necessarily the worst. .223 eats up metal targets more than .308 and 7.62 and the high sectional density high velocity long range 6 and 7mm are worse. As long as they are 1/4" or more a400 should hold up to lead bullets and any non magnum handgun rounds. For fmj rifle rounds you will want thicker and harder.
Cool. I could probably get a pickup load of these if I wanted to. I haven't shot one but they have a nice ring to them.
If you get a truck load I'd buy as many as can legally fit in a large flat rate box from ya.... can never have to many targets. Nice score. Heck my metal guy can't even find AR500 for me.... worth the money.
I'd be interested myself. I can get Ar-400, 500, but I usually need to buy more squares than I want. Keep us posted, thanks!
Sorry guys but I talked to my source today and these are actually pretty rare. Most are regular mild steel or stainless.
If I were you, I'd pick up matched pairs of SS/mild and plug weld them together, back-to-back. We built a big 'ol "safe room" for a client in his barn. Per owners spec. , 1/4" A36 plate on the outside with a SS 304 1/4 plate inside. They stopped 7.62 x 39 and most 7.62 x 51. Sure, the mild was cratered all to heck but it worked. Shot from 30'. I thought they were nuts until I saw all the test plates. If you can get them for free.......? Edit- The SS 304 was 1/4", not 3/16". I called the guy to confirm.