I apologize for not having a better grasp of modern lingo.
As for your comments Colombo, this is the most basic of infantry tactics and what you would see most professional militaries using to move across open ground with (with variation of course.) There are also things like Squad files and Squad lines, and if it's possible it would be backed up with armor, MICVs etc. You describe the best way to deal with it. Harassment from afar- but mechanical ambushes (boobie traps) should also be a big part of your toolbox, not just the far ambush and run.
Also consider the fact that the whole hide in the woods VC style things doesn't work nearly as well anymore - drones with FLIR and similar devices have added a new dimension to light infantry dismount tactics.
But you are right, I don't think there is an industrial army that could come close to making us fight it out with them on that level, not because we are so awesome, it's just that America is pretty darned big- and if we did have to fight a real army, it is more likely to be in cities, and we haven't touched on MOUT tactics yet (MOUT = city fighting, Military Operations in Urban Terrain)
I don't have a crystal ball and I don't know who the enemy could be, most likely a mugger in the street or a thug in my house, taking care of that is tactics that need to be discussed. In a long term SHTF there will be a variety of bad guys and some indifferent guys.
As far as gangs, they cary across the country - I don't know enough about it, but I would suggest everyone read this
http://www.military.com/news/article/2011/fbi-says-gangs-infiltrating-the-us-military.htmlIt might be nice to think of them as unorganized thugs, and that is what they look like to be, but don't be to confident.
The thing to do is plan well and train hard- and always remember the tactical principles.