For example, Utah law now includes provision specifically protecting the ability to tell or even show an aggressor you are armed without that action being a crime. (See Utah Revised Statutes, 76-10-506, especially (1)(b)(ii) and (3).
This law reflects the reality that many defensive gun uses do not include shooting at the aggressor; the sight of the (previously concealed??) gun is sufficient for the aggressor to break off his attack. The CDC has found, " that most firearm incidents are not fatal". John Lott writes in his More Guns, Less Crime that:
"[s]ince in many defensive cases a handgun is simply brandished, and no one is harmed, many defensive uses are never even reported to the police".
Attempting to quantify this phenomenon, in the first edition of the book, published in May 1998, Lott wrote that "national surveys" suggested that "98 percent of the time that people use guns defensively, they merely have to brandish a weapon to break off an attack."
--as quoted on Wiki Article about Defensive Gun Use
If well over 90% of "defensive gun uses" involve something like brandishing without actually firing, then either most DGUs are illegal or illegitimate, or most criminals can spin and run faster than most gun owners can pull a trigger, OR maybe the laws in a lot of places regarding brandishing don't appropriately appreciate the defensive value of brandishing a gun. If there is an option I haven't considered, I'd like to hear what it is.
Of course, opponents of private gun ownership will define DGU to be only those cases where a bad guy is killed, or maybe wounded. This minimizes the number of DGUs and causes criminal and accidental misuse of guns to be far more common than are DGUs. It seems natural to me that on an Open Carry forum most all would recognize the potential value of making a bad guy aware that an intended victim is armed and able to resist effectively. Obviously, OC does this passively without credible risk of accusations of "escalating". But referring to, exposing, or even "brandishing" a previously concealed firearm can--and according to Lott, in some 98% of cases does--have a very similar effect.
Maybe it is time for RKBA activists to work on decriminalizing what appears to be the most common mode of "using" a gun defensively.
EDIT to add: In the case of "warning shots" I can't disagree they are almost universally a bad idea. Maybe in some rare cases of being in the wilds and the threat being an animal, a very loud noise might serve the purpose to scare the animal off without material risk of where a bullet lands and while avoiding wounding and/or having to kill an animal.