This topic comes up often, and it usually ends up in a debate between about threat distances and responses to said threats.
Some feel that engaging a threat at an extended distance (the definition of which varies with the person asked) is unjustifiable.
Few years ago, I took the state mandated course to get my CHL. Instructor was a current police officer, who brought up this very topic; threat distances, and how to deal with them.
First, he pointed out that for our state, there needed to be three criteria before a person could legally use lethal force
1. Means: Meaning, the attacker(s) either had a weapon capable of inflicting lethal damage, or great bodily harm, or outnumbered the victim in a proportion that would allow lethal harm, or great bodily harm. Another possibility was if a 300# black belt attacked a 95# little old lady, he would be considered to have the means to inflict lethal force upon her. Disparity of force essentially.
2. Motive: The aggressor has to have shown some sort of overt display that he/she/they intend to inflict lethal damage or great bodily harm on the victim. Saying "I am going to kill you" would be one example. Pointing a firearm in a threatening manner would be another example.
3. Opportunity: This was simply explained as the aggressor being in range of whatever weapon he had. This obviously varies, and that point was expanded on later.
If any of these are missing, than in my state atleast, it's a bad shoot. Doesn't mean it will be prosecuted, but it doesn't meet the requirements.
So if a person says "I am going to kill you", and has a knife, but is 500 yards away, that person has means and motive, but lacks the opportunity. If that person was within 21' (actually a little more than that), than they would have the opportunity, and the requirements are met.
This officer, who instructed the class, made a point to say that if someone was 200 yards away, with a rifle, and had demonstrated the intent to kill you, it would be justifiable under the law to use lethal force against them. He introduced specific scenerios where this could occur.
It was pointed out though, that in our state, we have a duty to retreat. However, if retreat was not possible, than lethal force would be considered justified.
Similarly, he pointed out that the range may not be the commonly thought of range of a firearm.
For example, what range would be considered "opportunity" for an aggressor with a pistol? Some would argue anything over 50 yards, some might say 75 yards. He pointed out though, that a pistol is capable of killing someone from a much greater range than that. While it may be difficult to hit someone with a pistol at 100 yards, it's entirely possible, and the consequence of being hit is very serious. Death isn't a game, and it's not something you take a chance with.
With that in mind, I have layered my defensive collection. I would prefer to "outrange" any possible aggressor. By outrange, I mean, I would prefer that if I was placed in that situation, to deal with the threat at the fringe of the aggressors maximum range.
That would give me time, hopefully enough time, and distance, and the opportunity to utilize the "Nike" option. In addition, if I was forced into this situation, and a retreat was not possible, I would prefer that I could use something with enough accuracy to deal with the threat effectively and without risking harm to others, while making it as hard as possible on the aggressor.
Obviously, the aggressor is the one that sets the time/place/range of the conflict, so you really don't have a chance to decide where the aggressor is. But, if someone starts at 100 yards with a pistol, and tries to kill me, I would prefer to deal with it at that range, by using a rifle, than allowing him to close the distance and increase the likelyhood of killing me.
Long answer, and it's just my opinion, but it makes sense to me.
As for choices in weaponry, I think that depends on the specific situation, and where a person lives.
Assuming we are talking about civil disorder / Katrina / LA Riots type of situation:
If a person lives in a urban center, than I honestly see nothing wrong with a shotgun loaded with buck and slugs, or a pistol caliber carbine. I would see a M-1 Carbine, or a lever action carbine as almost ideal choices. I think an AR-15 would be even better, but some won't go that route.
If a person lives in a suburb, I think they should be capable of maxing out the range around them. For most that would mean 200-300 yards. That's not to say you would seek to engage someone at those longer ranges, but that it's smart to have the option if it was required. A rifle caliber carbine would be a smart choice, in my opinion, here. AR-15, AK clone, .30/30 lever action, Mini-14, those would be the top choices.
In addition, the carbine/rifle option gives other advantages, especially with optics. The ability to hit a precise target is valuable. The idea being to take the fight out of an aggressor ASAP, while minimizing risk to others in the area.
For an example: Say someone is behind a car, shooting in your direction, at 75 yards.
Yes, it's possible to hit that person with a shotgun loaded with slugs from a shotgun, but there is an increased risk of missing, and a miss increases risk to those nearby.
A pistol is similar. Yes, a hit can be achieved at that range, but the odds are less likely, and the risk of a miss is also increased.
An accurate carbine, especially one with an optic of some sort increases the odds of hitting the target, and ending the threat, while reducing the risk of missed shots that could hit others.
