A couple of years ago at swat training we found some plywood targets that were attached to metal fence posts. Most everyone was shooting target ammo which I think was American Eagle, I don't know what grain it was. Upon seeing this with a .40 cal bullet, I decided to get my conversion barrel and some target .357 Sig ammo and see what it would do.
This picture is the .40 cal bullets hitting just the fence post.
This picture is the .357 Sig bullets hitting the plywood and then going through the fence post.