Preppers and other survival-oriented individualists debate the optimum survival weapon. The first generation after Armageddon will have smokeless firearms and ammo. The hope is that things will mend themselves and people will get back to struggling with making civilization work. But if the recovery is extended eventually stocks of centerfire cartridges will dry up. We may want to consider alternatives to that tricked out black rifle and consider an alternative.
Hunting Bow & Arrow
Some advocate the bow and arrow. Weapon and ammo can be manufactured with material at hand. The bow has served mankind for centuries, even millennia, with the last major battle with bow armed militia versus the gun wielding English during the English Civil War. The Comanche’s traded their muskets and muzzle loaders for the traditional bow and arrow until the introduction of the repeating rifle. The bow is quiet and the firing rate much higher than typical muzzle stuffer. The bows limitation is range versus a rifled gun and the amount of ammo carried, arrows are bulky.
Muzzle Loading Flintlocks
But if you have your heart set on a gun, it would be hard to not consider a flintlock, Hawken pattern in .50 caliber or preferably .58 caliber. With the velocity limitations of black powder, you need the heavier bullet. A .58 caliber 480 grain backed by 60 grains of black powder will hit 1,100 fps at the muzzle and should do you for nearly anything on the North American continent. A .36 caliber for small game would round out a good rifle battery. Throw in a double-barreled shotgun in 10 or 12 gauge and you would cover fowl. An alternative is a single barrel solution is a smooth bore musket cut down to 18” or so and loaded with shot. Why flintlocks? You need to be independent of any manufactured goods, including metallic cartridges and caps. Except for springs a muzzleloader well maintained can last generations. It may not be authentic, but a stainless barrel plug and barrel would be good idea. Lead could be recovered from wheel weight and batteries though there are some safety problems to overcome, and bullets molded. Minié-balls would be the choice, faster to reload, better ballistic shape and a better sectional density.
Types of Propellants
As to propellants, black powder compared to modern propellants sucks, with only about 40% of the materials converted to gas, the rest is fouling deposited in the bore or smoke. But it can be made. Potassium nitrate (saltpeter), charcoal and sulfur. The only thing that maybe problematic is sulfur, but the other items are common. Potassium nitrate can be recovered from animal or human urine and ashes. Charcoal can be made from nearly any source but willow is the preferred material. Charcoal is just heated wood without air. The woods impurities are driven from the wood as wood gas leaving mostly carbon behind. This is the fuel. Potassium nitrate is the oxidizer and the sulfur acts as a catalytic fuel by lowering the temperature of ignition which increases the rate of combustion. With proportions of 75% saltpeter, 15% softwood charcoal and 10% sulfur. French war powder changes charcoal to 12.5% and 12.5% sulfur. No one formula and some preferences are national. Sulfur absorbs water making it corrosive, you need to clean and oil your weapon soon after firing it, but stainless-steel components are more forgiving. Flint is available and common and would be your primary ignition device. Need to learn flint napping, good for the archer as well. You will have to form your flints to work with your gun. Vegetable oils can be used as lubricants if necessary, but there are others. Some will demand regular maintenance, but you should be taking care of your primary survival tool anyway.