Dear Jim and Family,
In the beginning of a collapse, you carry a concealed weapon, and deal with the police if you have to use it. Gunfights [typically] last 4 rounds or less, and its usually just one attacker. In theory, after the fight and you’ve survived, you get it back, eventually. Use a revolver or automatic, your choice, just be sure its small and light enough you always carry it.
As the collapse deepens, you start encountering more and more threats, packs of them. They attack your vehicle, they go after your home, they try to stop you with roadblocks and hostages. It only gets worse as your survival makes you a bigger target for them. The Golden Horde  descends and committed amateurs require a lot more firepower to dissuade. As we’ve read in the Argentina diary by FerFAL, you need volume of fire, and cheap ammo so you can fire lots, spray and pray to drive them off. JHP  if at all possible. At this point, the police are coming late or not at all, and investigations are perfunctory and dismissive as long as the bribes flow.
Traditionally, these collapses don’t last, and things get better again, with more happy motoring and mass consumption of products… but that’s the past. The future is a touch more simple and ugly. The mass quantities are over because the cheap energy is over. Along with those are mass ammunition supplies. Eventually, after years of self defense shootouts and MZB  assaults, you start getting low on ammo. You reload your brass, you shoot semi-auto. You pick up your brass but you start running out. It doesn’t fit right, its got overpressure damage due to firing in a dirty chamber, incipient case-head separation, cracks, etc etc. What to do? Your automatic pistol needs specific care and feeding to stay reliable. What indeed…
The revolver is a finicky beast, despite what you’ve heard. Carefully tuned by a decent gunsmith they’re a dream to shoot and usually very accurate and amazingly reliable (tuned, mind you). Replacement parts are not drop in, but require fitting and polishing by a smith, which will cost around $1,000. That said, they’re relatively simple and most importantly: they don’t throw brass. After all the MZBs are mostly dead, a few loners are left wandering around, most of them wary of you or harmless. You’ll still need to carry a gun to be safe but you probably won’t need a rifle for day-to-day chores or killing snakes in your garden. A revolver is ideal for this job. You can save and reload the brass because the empties are still in the gun. You don’t have to crawl around in the dirt, looking for the .40 S&W, one of 43 [pieces] left in your collection, you are sure its over here somewhere. With a revolver, the brass is in your hand.
The Peak Oil collapse is not quite generational, but almost. In some places it will be. In others it won’t. The recovery that comes after about 20 years of misery and shortages and temporary bouts of violence (or true anarchy), will eventually end. After two decades of poor or no-police presence, distrust will be such that going armed is the only way to go in many places. However, you will probably find yourself not needing it very often because those 20 years very effectively killed off the most aggressive people, and organized the smart ones into those more able to use, not kill the peasant class, which may include you. You won’t have access to spare brass (copper is in short supply now, and will be expensive or impossible to get by then), so having brass is a good idea, stockpiling it and the dies and such needed to load.
As to caliber for your revolver… well, in the old west gunfighters used .35 caliber (slower that .357s), lawmen used .44 and .45 caliber. While the .45 LC cowboy action pistols are fun shooters, they’re slow to unload and reload, which I’d call a major problem. I’m aware of bullet swaging hobbyists (make the bullets from lead wire and copper tubes) who can get .454 Casull velocities out of .45 “Long” Colt revolvers which are built strongly. It also bears point that the .44 Magnum can be easily loaded at .44 Special velocities which is more like a .45 ACP in recoil and every bit as effective and comfortable to shoot, so as long as you’re reloading anyway, load it to match your preference in recoil. There’s also the .41 Magnum, which is between the .357 and .44 in power and recoil, basically a hotter 10mm/.40S&W. Taurus is fond of the chambering for some reason and is selling quite a few models with it, which makes me wonder. Besides two-legged predators, you’ll be dealing with feral dog packs, cougars, and black bear which have been eating the dead and see you as a meal (no really, that’s why the lions in The Ghost and the Darkness were eating people: poor disposal of corpses taught them that people were food). While animal attacks will be infrequent, you must carry a gun to protect yourself.
The short of it is, buy a sturdy automatic for the first and second parts of the collapse, and a revolver for the third. Best, – InyoKern