I shoot USPSA and per the rule book the minum distance for steel is 23 feet. For those who shoot USPSA and are members this is the rule:
2.1.3 Minimum Distances – Whenever metal targets or metal hard cover are
used in a course of fire, precautions must be taken so that competitors
and Match Officials maintain a minimum distance of 23 feet from them
while they are being shot. Where possible, this should be done with
physical barriers. If Fault Lines are used to limit the approach to metal
targets, they must be placed at least 26 feet from the targets so that the
competitor may inadvertently fault the line and still be outside the 23
feet minimum distance.
Has anyone seen this video on youtube.
http://www.youtube.com/watch?v=0ABGIJwiGBc
That's what can happen when you shoot at steel if it's not of the proper type for handgun or rifle.