If I were to have only one, or two, or . .

If I were to have only one rifle, I would consider myself a poor sorry son of a bitch.

In spite of the revered Colonel Cooper's teachings, I would not be satisfied with a Scout. Even JC wasn't happy with a single Scout rifle, even after he had a Steyr built to his specs. My Scouts and/or Pseudoscouts don't cover all of the bases either.

So neither Cabinet Man nor I have only a single rifle, and we seem to keep acquiring them, he at his customary rate and I at mine, with various purposes or roles attached to each.

But the question lingers. So flesh it with some assumptions:

TEOTWAWKI. Your stock of ammunition is what you have around you, possibly supplemented by what neighbors can spare or trade away.

Hits count. Fred gave you the Rifleman patch at a recent Appleseed clinic and you're confident to hit what you can see out to 400, maybe 600 meters. The rifle shoots better than you do.

Fixed, defensible homestead. What you've acquired through the years is still under or around you, and one purpose of the rifle is to keep it.

Partially organized but State-less attackers. Looters, vagabonds, rabble who were created in a city they find no longer habitable. Some may be trained as soldiers. They have no supply chain.

If any US troops show up, your mayor and sheriff stride out to meet them, say everything is fine, offer them breakfast and ask "who's the President?"

Golly. Any of the .30/7.62mm's cited in Boston's Gun Bible would do.

Change assumptions, then. Instead of equipping your own self and maybe some neighbors for Post-Housing-Bubble, let's say you're fielding an army of a few thousand, and you have a small country's treasury at your disposal while the copper and yellowcake mines are still producing.

That's easy. An AR15, converted to piston operation instead of direct impingement, internally dehorned, possibly carbon fiber instead of aluminum, chambered in 6.5mm x39 Grendel. There may be no full- or burst-auto. Every soldier starts out on a 16" barreled carbine and everybody qualifies with between 600 and 1000 rounds per year.

Your Brit expat DIs and Devil Dog marksmanship instructors find the better of them and graduate them to 20 or 22" barreled designated marksman rifles.

The crew-served weapon is the American contender to replace the M249, still firing 6.5 G on disintegrating links.

Any other set of assumptions probably lies somewhere in the middle of these two extremes.