I know this is a little bit of and over do, for most shooters, but the US Army has a publication which may be useful, as well as interesting, for researching the logic of range safety. The following link is from the US Army publications directorate and includes a good amount of information about surface danger zones, charts and tables referencing range planning. This is used to determine the amount of risk applied to the many types of ranges in the armed forces (the USMC use this book as well). Just skip the bombs, shells, lasars, and look for small arms ranges, the topic begins on page 23.
Download this Department of the Army Phamphlet 385-63. at this location: http://www.apd.army.mil/pdffiles/p385_63.pd
There is also Army Regulation 385-63, which has less information. Do not confuse the two. Get DA Pam 385-63.