Commercial ammunition for centerfire rifles and handguns has always been relatively expensive. Because of this, few manufacturers or dealers offer much in the way of variety. To some degree this has changed with Federal and Winchester both offering Premium bullets in their popular hunting cartridges; but yikes, does that stuff cost!
If you have been shooting a while, possibly you have saved your empty brass cases. These represent the greatest expense in ammunition assembly cost and, IF Boxer Primed they can be reloaded and fired again for many loadings.
Want to own 100rds of .300win magnum with 180gr Barnes Triple X boattail bullets? Be ready to pay about $300 for 5 boxes of premium ammunition. Or buy two boxes of Barnes bullets for about $90, $4 for primers and $30 for a pound of powder. If you don't have fired brass cases, new ones are about $75 per hundred. Can save about $65 if you use Sierra GameKing btsp bullets which are also superb in quality.
Handloading offers you a means to assemble better ammunition than you can buy at any price, because it can be tailored to your rifle or handgun. Shotshell reloading is also viable, but won't be discussed here.
Most handloading manuals cover the basic handloading processes. Lyman is the oldest manufacturer of handloading gear and bullet casting equipment. They also make Blackpowder rifles and handguns. Their basic manual, shotshell manual, and Cast Bullet Handbook are classics. Not my first choice for loading gear, but their 310 tools are what I cut my loading teeth on, way back when. Lee Engineering, Sierra Bullets, Hornady Bullets, and The Accurate Smokeless Powder Loading Guide comprise what I consider to be the better loading manuals. Nosler and Barnes manuals are also out there and may be of interest if you shoot their specialty bullets.
If you don't Handload, you'll likely require a different rifle or handgun to perform the different jobs you'll likely need firearms to do. The .308win can be loaded with cast bullets or even .32cal pistol bullets at very low velocity. You might want such a load to hunt take small game without meat damage. You might want to load a jacketed hollowpointed pistol bullet to high velocity to kill varmints. Jacketed .30cal rifle bullets come in a weight range from 110gr to 240gr. Light loads to maximum power loads are all possible for the handloader. One rifle or handgun can serve many uses.
One term may be confusing: grain. Bullets, and smokeless powder is measured in weight unit of grains. One pound contains 7,000 grains. One hundred 70gr bullets will weigh a pound. One pound of Unique powder will load 1,000 .357magnum ctgs with a 7gr loading, if you don't spill any. Smokeless powder is not explosive, it generates pressure by burning. Powders are fast or slow burning depending on their burn rate. Generally, slow burning powders produce the highest pressure and therefore velocities; but this is an oversimplification.
Handloading is a primary skill for any survivalist. Unknown ammunition that may be acquired can be harvested for components with a bullet puller. A collet type puller is fast. Bullet pulling enables brass, powder, and bullet to be re-used, presuming you can identify the powder. Foreign loads might be problematic, but with a loading manual, scale and some study you could likely salvage the powder with confidence in a SURVIVAL situation...
If you are in process of learning the .45acp, handloads assembled with mild/moderate charge of Unique and 200gr lead cast bullets will not only be affordable, but enable easier familiarity with trigger and recoil of the piece. Might also try a .22lr Conversion Unit like the one by Jonathan Ciener. The 200gr lead bullet though is also a good choice for small game hunting.
The generic .45acp 230gr ball ammo is also fine for practice or carry. Remington or Winchester are preferred for brass quality. You can almost buy loaded ammo at WallyWorld for what the brass alone costs. Don't miss those deals...
The AR-15 becomes a very viable Assault Rifle when loaded with 75/77gr match ammunition. Costs about 40cents to load these yourself using once-fired military brass; or buy them new for $30-$35 per 20 from commercial sources. tjconevera.com sells 600 Hornady 75gr boattail hollowpoint match bullets plus 600 prepared 1x fired military 5.56NATO (lake city or winchester) for $140 delivered. Hard to beat this, but you can find 77gr Nosler bthp match bullets in 2000qty and unfired Lake City at MidwayUSA.com, Grafs & son, MidSouth Shooters Supply, Wideners, PowderValley, are other component sellers along with Pat's reloading you may want to shop with.
I am stoked on the AR-15 with heavy bullets. Much less expensive to by an AR-15 than a good .308 chambered mil-spec in AR-10 or M1a. Cheaper to load the .223 than the .308 as well, easier for a novice or expert to shoot the AR-15 well, and with 75/77gr bullets the rifle is capable of precision at great distance. Note that I stipulated "the rifle"... An M4 short-barreled carbine will perform much better with the heavy bullets, but can't deliver accurate fire much past 400/450yds. This may be enough, but a 20" AR-15 rifle with 7 or 8 twist barrel can be very accurate to 600yds or further.
The .223 remington in a bolt rifle with 6.5 twist has shown great accuracy to 1000yds shooting 90gr bullets. Contrast this to the 6mm bore which the .243win typifies and the heaviest commercial loads for hunting are 100gr, with 105/107 being heaviest match commercially loaded. The AR-15 is very capable when loaded up to its abilities.
Handloading? It just enables you to do about anything you want with your rifle or handgun. You can hunt with an AR-15. Might want to try the 60gr Nosler partition, or see what Barnes is selling, but if all you've got is a magazine full of 75gr match ammo, any deer you hit well with it will go down or leave a good blood trail. The defensive rifle is your first priority. Owning handloading gear enables you to make ammunition for any and all purposes. The AR-15 can be single-loaded with specialty loads that might be longer than magazine length. Many shoot lead bullets in their ARs as well.
Most rifles will deliver better accuracy when bullets are seated into contact with the rifling or just short of it. Unless you handload you will never know how your rifle might perform with just some minor tweaking. Bullet seating might change your rifle from a 5rds into 1" at 100yds to 5rds into .5" or less.
I loaded a bunch of .308 sierra 168 match bullets to be just functional in M1a magazines, used the Sierra precision load in the manual, and shot them from a plainjane rem 700 varmint special routinely with .4" groups at 100yds and under .7" at 200yds. Almost boring how accurate that rifle was from the bench... For best performance, handloading is the answer.
Berger bullets, Lapua, JLK, and other super-high Ballistic Coefficient bullets are not available in commercial loadings. Sure, you can own several rifles for many different purposes or you can own one and handload.
If you've got loading gear and components, you've got experience and ability that mean you have much to offer your friends and family for barter. Might think about investing in a quality basic kit like the RCBS Rockchucker supreme kit and then buy dies for your weapons and others your friends or buddies have. Advise them to buy their die sets and components so you can load for them.
Most popular rifle and handgun cartridges will include: .223rem, .243win, .308win, .30-06 Springfield, .300win mag, .270win, 7mm rem mag and maybe the .22-250 for rifles and .380acp, 9mm Para, .357mag/38sp, .40S&W/10mm Auto, .45acp, .44mag/.44sp and .454 Casull/.45Colt. In Alaska or Montana, might add the .338win and .300weatherby. And ooops, forgot the .30-30win, it is popular everywhere...
Lee Engineering sells aluminum cast bullet molds for about $25 with handles. These are a good value and Lee has many bullet and calibers to select from. Owning a mold for your rifle and handgun assures you of bullets if you have access to lead. Tire shops might be a good source for used wheelweights you can melt down for bullet casting alloy.
As far as Components go, best way to store primers and powder is as assembled ammunition. Yet, primers last almost forever if kept dry and out of humid conditions. Smokeless powder should be stored in original containers and in correct conditions will last 20yrs or longer. Never remove primers from orig packaging. If stored loosely, like in a jar or can, the potential for ignition is too great to risk, so keep them in their tray or loading strips and avoid a catastrophe...
From what I have seen on the internet, the days of cheap surplus ammunition which many guys blew down the range on weekends has ended. If you shot tons of the stuff, hope you had boxer primed ammo and kept your brass. Having the brass makes loading that much cheaper. Other than the steel-cased or easter European commercial stuff like S&B or PRVI, generic fmj American ammo is going for about $1ea. PRVI and S&B have good boxer primed brass, but their bullets are not very esteemed for accuracy.
There are sealants for those who worry about water immersion. These usually are the same type guys who choose an AK-47 because it will function fine if immersed in mud or gunk. Don't soak your ammo in the lake, or package it well if caching is your intent. Might also seal your primers and necks if concerned.
Handloading is a skill every gun owner ought cultivate. Undoubtedly, you will be glad you did at sometime in the future.