how hard would it be to make bolo shells? i have a post-apocalyptic setting, and bolo shells sound like the perfect ammunition for the story (vampires), but idk the logistics of my character getting her hands on them or if it could be practical for her to make them herself.
As far as I know, it should be fairly easy. Shotguns shells are, generally, more forgiving to handload than most firearms. The hardest part would be making the bolo itself, which should be doable if you’re familiar with making bullets, have a suitable supply of metal, and some steel wire to connect the weights.
So, let me explain terminology here, quickly.
Handloading is the practice of manually preparing your own ammunition for a modern firearm. This requires a few supplies. You need casings (sometimes called brass, though with modern shotguns these are plastic), bullets (as in the actual projectile you’ll be firing, sometimes simply called, “lead”), powder, and primers.
In this case, your character would be making their own exotic projectiles. When you’re looking at a normal firearm, you’d usually want to get your own supply of unused bullets, though with some practice it is possible to make your own lead. It is possible to make bullets from materials other than lead. For example, you could use tin, copper, or other soft metals. Depending on density, they’ll have different ballistics from conventional rounds.
It’s technically possible to melt down harder materials like steel, and make bullets from those, but the resulting round would damage the firearm’s rifling when fired. These are sometimes used, with a soft metal “jacket” layered over the harder core for armor piercing rounds. (These work because the harder core will not deform as easily on impact, and will deliver more force to a single focused point, rather than expanding out, distributing the force across a wider space.)
With powder, it’s worth remembering that modern firearms do not use black powder. If you’ve found a recipe for gunpowder that calls for potassium nitrate (strictly speaking, any nitrate will get the job done, saltpeter is just the most common suggested ingredient), sulfur, and charcoal (sometimes you’ll see this referred to as just carbon, but you do need some of the unburnt wood cellulose for the chemical reaction), that will produce black powder. Now, this stuff does work as a primary propellant, but it will also cause any firearm more mechanically complex than a revolver to foul fairly quickly. The issue is that black powder burns less efficiently than modern smokeless powders. This means your unburnt powder will form as residue in your barrel and in any exposed mechanical components. Additionally, the sulfur is mildly corrosive, meaning it will also damage your weapon from prolonged misuse. Not that it matters, but black powder also delivers less force, so your bullets would have less range, and penetration.
It is (theoretically) possible to synthesize your own smokeless powder after the end of days, but it would require getting access to some fairly specific chemical supplies, and some fairly sophisticated lab work. Primers are a similar situation, not impossible if your character has a strong background in chemistry, but not exactly the kind of thing you or I could whip up in a desperate moment.
That said, handloading is fairly common among some gun enthusiasts, so the supplies are out there. How long those would last after the end hit would depend heavily on how long people were able to hold out before dying. If the apocalypse claimed the vast majority of its victims in the first few hours, the existing ammunition supplies could last for decades. On the other hand, if the apocalypse was slow, and people were dying out over the decades, then these supplies could be incredibly scarce.