Ah, a classic SHTF discussion. I guess I will dispense some of my opinions, and get a few groans from the audience.
I've talked about it before, but I just want to take another look at extreme range shooting (i.e. anything past 300 or so yards).
First, most people do not have the skill for this. Note I say most!
Lets face it though, even with a telescopic sight the vast majority of shooters would have difficulty landing good hits past 300 yards without a benchrest. Missing twice before nailing the target doesn't count; if it was a game animal the thing would already be hauling for the county line. If it was an opponent they probably would have already started running for cover and alerted their buddies of your general position.
Next let us consider hunting at such extreme ranges. As stated before, there is the good chance of scaring off the target. Your chances of being unable to track the animal are much greater too, due to the fact that hits are less precise at range and you need to travel a ways to get on the trail. This is not a good use of time and resources. The likelyhood of the hunt's success goes up exponentially if a stalk is executed to get closer to the animal.
Now onto people defense. Extreme range shooting is very hard to justify. I have thought about the "Killzone Defense" before:
I think you make a good point. Some people seem to have this vision that when the SHTF Slayer's "South of Heaven" kicks on, the sky turns black, and people throw on torn leather jackets, tight pants and jackboots to start executing human wave attacks against the few pure of heart.
I think the guy in the article I linked to makes a good point. Somebody (sane) isn't going to be sitting on the roof of their house with a high powered rifle repelling invaders. There are so many other things to do, like secure water supplies and repair any damage to your residence. You still need to eat, sleep, and use the toilet.
Plus there is the whole morality issue. Most people are not out to kill and commit crime; how can a reasonable person just shoot anyone who walks onto their property?
I'm am not ragging on .308 rifles, they do have their uses. People just seem to paint them as "Thor's Hammer" when their advantages over other calibers are more marginal.
And there is a definite downside to .308 ammunition, namely that it is expensive. Twice as much steel cased .223 and 7.62x39 can for the same price as .308, and even the brass cased .223 is about 30-40% or so cheaper.
Let us move on to another controversial topic, namely the pistol caliber carbine. I think there are many reasons to reccomend these:
1.They allow commonality between a sidearm and a longarm (as mentioned before).
2. Pistol ammunition is cheaper than rifle ammuntion, for the most part (allowing more practice and a larger stockpile for a given amount of money).
3. The PCC (new acronym!) is reasonable in price, comparable to a pistol. While the Beretta is in rifle territory at $650; a Hi-Point sells new for around $200, with the Kel-Tec not too much more. Both the Hi-Point and Kel-Tec are cheaper than a full size rifle.
4. Many people argue that most PCCs offer only marginally improved ballistics over a pistol and cannot compare to a rifle, which is true. However, try shooting a pistol at 100 yards, then a PCC. While the ballistics aren't great at 100, they are still useable.