Machine guns ARE still legal to own in the US. its just that at $5-20K each the average joe can't afford to own one. The rich still can, but the rest of us can't afford our 2nd amendment rights. But thats a topic for another day...
I'm not a big fan of the m16 family, but that seems to be the current example so I'll run with it. Yes I agree an ar15 is not the best option for home defense. That is if you live in a sardine can apartment or in the suburbs where houses are packed tighter than Elton John's backside. In that case, a shotgun or pistol w/ HP ammo is your best bet.
However, alot of us live out in the country. Out here you need more range and power than a pistol or shotgun can provide. (preferably something in the .30cal range.)
Sure bolt guns are fine for single targets, semis are good too. But what about a truckload of armed men? I hope you're a good shot with your hunting rifle. And if you've got a mini-14 I hope its alot more accurate than the one I had.
Now this is the point where someone says "a truckload of armed men? thats redikulus!"
Well maybe it is, maybe it ain't. You can never tell what the future will behold, and I think its good to be prepared.
What happends if you live on a ranch near a major city and that city is attacked with a WMD of some sort? Don't say it can't or won't happen. Terrorists are trying to do it, and will continue to try.
I'll tell you what will happen, hundereds of thousands perhaps MILLIONS of people will be fleeing the city. The ones that make it out may be infected with disease, or covered in radioactive dust or other harmful chemicals. Where will these people go? Wherever there is food and shelter. Where is food and shelter? At your ranch thats where!
Will they ask politly if they can live in your house and eat your family's food? Doubtful.
Desperate people take desperate measues. It not too hard to believe that starving people would band together and try to take over a ranch or farm that won't share its livestock and crops.
If you depend on those livestock and crops to feed your family, you better be willing and able to defend them.
Now thats just one scenario that my paranoid mind can conjure up. But what it boils down to is one must beable to defend himself and his family under any circumstances. And thats hard to do with a board with a nail in it.