Granted, attempting to disarm a mugger should be a last recourse, but should the need arise this tape provides good instruction on how to practice the techniques. It breaks down techniques into the steps of redirecting the line of fire, controlling the weapon, and then disarming the gunman. It clearly teaches one response to each attack. While in some cases I personally prefer a different response to the one they teach, it does provide potentially workable disarms should one have no other recourse but to attempt to disarm their attacker. The practice guns they use and recommend are the ASP Redguns.
Standard disclaimers apply.