[@RaeoftheLight] Even weapons have a 'use by date' so a pristine automatic rifle will be near impossible to come across in anywhere but an abandoned military base. However, ratchet and homemade weapons will be far from sparse - metal may rust and wither with time but steel is particularly durable.

Handguns etc while not common are certainly not rare by any stretch. I would think also that the upkeep and maintenance of such weapons would be emphasised and key during these times - thus maybe the reason why they are not used by everyone/ why they are still around to date.