Minimum range to steel is 10 yards in IDPA; used to be 10 meters in USPSA but I think they allow it closer now.
CAS sets it closer than anybody else; one of the three worst hits I ever took was at a CAS match but it was a setup fault; the plate was not perpendicular to the line of fire, so most of a bullet deflected off of it and hit me on the next stage over. Had a knot and bruise just above the knee.
Another was off of a dinged up Pepper Popper, even at 10m the spatter was fast enough that I felt the blow to the ribs and shortly heard another shooter say: "Your shirt is bloody."
The most recent, and worst, was off a non-metallic target. A .45 Minor bounced straight back off a synthetic timber block being used in lieu of a bowling pin. It hit me on the middle finger right below the WML. I shifted to the other hand and finished the stage dripping blood. Patched it up and shot the last stage of the match, then went to have the wound glued shut. Fortunately we were shooting WHO, so it was my left hand that got gouged. An inch up and it would have broken my searchlight, an inch to the right and it would have hit me in the face. Seems I was not the only victim of bounceback that day, just the worst hurt. They quit using that stuff for targets.