Action shooting is a dynamic sport. Because we're moving and shooting and reloading, we need to be alert - and careful.
Whatever we do in practice, we'll do in a match (and usually faster).
The Four Rules of Gun Safety
Always treat every gun as if it's loaded.
Never allow the muzzle to point at anything you don't plan to shoot.
Keep your finger off the trigger and out of the trigger guard until you're ready to fire the gun.
Be sure of your target and everything beyond it.
If you know and observe the Rules of Gun Safety,
USPSA Safety Rules
To help everyone pay their best attention to safety practices, the following is a summary of the USPSA safety-related rules, from Chapter 10 of the USPSA Rule Book (current version is "Handgun Rules for 2014"). This summary is not exhaustive; the complete rules are in the book.
Accidental discharge (AD) - An AD is a shot that you didn't deliberately fire while engaging a target; any shot which goes over the backstop or berm; and any shot that strikes the ground within 10 feet of you (with certain exceptions). ADs are also shots fired when you're loading, drawing, reloading, transferring the gun between hands, or correcting a malfunction; during movement (unless you're actively engaging targets); or while unloading at the end of the course of fire. The cure for this, of course, is good control of your muzzle and trigger finger (Safety rules 2 and 3).
Unsafe gun handling - We have to be aware of our gun and keep it under control. In order to keep us, the spectators, and the sport safe, the following (and certain other problems) will result in match disqualfication:
Handling a firearm at any time other than when in a designated Safety Area or while under the direction of a Range Officer (Rule 10.5.1)
Having a loaded firearm at any time other than when specificially ordered by the Range Officer (10.5.13). (Keep it in the holster, unloaded, until it's your turn to shoot and the Range Officer gives the "Make Ready" command.)
Handling live or dummy ammo, or handling loaded magazines or speed loaders in a Safety Area. (10.5.12)
Letting the muzzle point uprange or past an imaginary plane that goes 180 degrees from right to left, parallel to the backstop. (Also known as "breaking the 180".) (10.5.2)
Drawing a handgun while facing uprange (10.5.16). (Some stages will have you start while facing uprange, but you can't draw until you've turned to face downrange. If you're unclear about this, ask us!)
Letting the muzzle point uprange more than 3 feet from your feet while drawing or re-holstering (10.5.6).
Dropping the handgun during a Course of Fire (that's any time after the "Make Ready" command and before the "Range Is Clear" command). (10.5.3) It doesn't have to hit the ground; losing grip and "trapping" it between your arm and body still violates the rule.
Sweeping your body with the muzzle during a course of fire (10.5.5) (This includes sweeping your hand or arm. Don't hike up your belt or pants by grabbing the bottom of the holster - your hand will be right in front of the muzzle.)
Failure to keep your finger out of the trigger guard while loading, reloading, correcting a malfunction, or moving (unless shooting while moving). (This is a big one, and we watch for it especially.) (10.5.8, 10.5.9, 10.5.10)
Improperly holstering a loaded handgun (for instance, holstering with the hammer cocked but the safety off, or holstering a revolver that is cocked). (10.5.11)
Wearing or using more than one handgun during a course of fire (10.5.7). (Note: You cannot have an additional concealed carry gun while shooting USPSA. You can use your carry gun for the match, even from concealment, as long as you follow the other USPSA rules.)
Picking up a dropped handgun (if you drop your gun, the Range Officer must retrieve it, whether loaded or empty.) (10.5.14)
Firing at a metal target from less than 23 feet (we'll help by setting them up at a proper distance and providing boundary lines - your job is to not voilate those boundaries) (10.5.17)
Also for safety's sake and to protect the sport, unsportsmanlike conduct and prohibited substances (alcohol and drugs) will result in disqualification (sections 10.6 and 10.7).
This may sound like a lot, but again it's based on the Four Rules of Gun Safety and good old "common sense", which we should practice all the time.