Isn't it easy enough to make ammunition for modern rifles? I'm not a gunsmith or gun engineer, but it doesn't sound difficult to reuse casings and make ammunition. Of course, one would still need to make: * pointy bullets with steel scraps and some cast/mold and some coal-powered oven (you see a lot of youtube guys melting metal with not that much equipment) * gunpowder and a primer, and might not require a lot of ch…
Factory ammo is just as cheap (even though labor is free, and equipment costs are not counted at all for the make your own) and takes less time so militarizes use it as does anyone who doesn't need the best quality.