can't do anything unless he is threatened or, in some states, you're stealing something. Just walk away and it's over.

This does, of course happen, if rarely.

for the owner of the gun to show how stupid he is.

Never, ever pull a gun on anybody unless you plan to shoot them with it. And of you shoot them expect them to die. Using a gun to defend property is just asking for trouble.

drawing and pointing a firearm when there is no threat can catch you a charge of "assault with a deadly weapon" felony charge

Not his house, none of his business. He may call police, that is all.

the only justifiable move, in my opinion, is for the detainer to get a good description of the people and if in a car, a good description.
If there is no threat of force from the people leaving, let them go.

I will admit up front what I want and what I expect to be a sensible reaction from anyone.

If there is no reasonable(DING!) bodily threat perceived(DING!) by those involved, then there would be no excuse to escalate. Pretty simple to me.

But why the guns, then?

I was taught, and believe, that you do not pull a gun unless there is chance you might NEED to use it. Detaining suspicious others is not, necessarily, a good reason to do so.

...and all the ingredients are in present.

Not good.

threatening other people with a gun would be the best ingredient for shit spiraling out of control. It makes it REAL and MORTAL-I think people react to that.

The legal use of lethal force has very strict limits. The scenario presented does not come close to qualifying. In this given scenario, any gun held in the hand is done so illegally (brandishing).

The "reasonable belief" standard is "ability, opportunity, jeopardy".

Since the detained people are presenting no threat, lethal force cannot be used against them. Should they choose to walk away, no force can be legally used to stop them.

If these folks are not *breaking and entering* it's none of your business. If you're concerned, call law enforcement. If these folks are *breaking and entering*, this is a crime; call law enforcement, if you are so motivated to confront them (I wouldn't unless it was my house and LEO response is very slow and people are in danger) you may be injured or killed for your trouble.

OTOH if you are the folks attempting to enter and are confronted by someone with a gun, there is no way I would try to walk away. These people could be nuts. I'll wait for the cops.

justified in showing a firearm to begin with. Observe from a distance and report, certainly - and if the person runs you should get a good description and a direction. I'm not opposed to approaching, questioning, or intervening, but only if you're able to do so in a way unlikely to escalate (especially if you're armed), and you're willing to back away if the situation starts to spiral.

A firearm should only be pointed in the case of genuine and serious defensive need, and if you're concerned enough to draw it on approach then you shouldn't be approaching at all (if there's any option not to)...

had not committed any crime yet, the gun guy has committed "assault with a deadly weapon" and false arrest if he has detained them.

This was a house that was foreclosed and vacant for months. I might react if it were occupied but in its current state, I say 'no way' and stay out of it. People watch to much TV.

and notify the police. They should never have been confronted at gun point to begin with. Some gun owners need to get over the notion that they can just step in and detain people, it can be done legally but there are very clear rules. I for one am not going to confront possible robbers and risk being shot, killed or badly injured unless my life is being threatened directly.

I don't like training requirements, but these kind of actions suggest to me that gun purchasers, and carriers in particular, need to receive some education about what exactly does and does not warrant deadly force, what is and is not self-defense, what actions should be taken before or instead of drawing a gun, etc. I'm not asking for live-fire shoothouse exercise with two days of class time, but maybe something along the lines of the computerized license exam for drivers. Free video, test questions on the law, maybe a card or certificate if that's how you like it. I've heard too many people brag to me about their states' liberal gun laws when they don't understand what it really says.

In Alabama, you may use deadly force against anyone committing robbery or burglary of any degree, or in the process of unlawfully and forcefully entering, or has unlawfully and forcefully entered, a dwelling, or residence.

So in Alabama, if you are caught committing robbery or burglary of a house, unoccupied or otherwise, you can be shot for it.

Now if you detain them instead of shooting them, and then they run away, I don't really know what your options are. Are they still then considered resuming their previous activity of robbery or unlawful and forceful entering?

Given Alabama law that I'm allowed to shoot home invaders and/or burglars/robbers, I would think that if they got caught in the act and did not comply and got shot that a jury would have a hard time convicting, but I don't know.

Outside the home never risk life and limb for property. Maybe yell at them that should work most times to scare them away, either case dial 911.

Inside the home do what you have to...