[Matt W]

The KFS would need a supply of stainless steel scrap

Stainless steel scrap is a good source of chromium. I believe that about half of the chromium used in the USA is derived from recycling. Or - of course - the KFS could just recycle it to make the Mini-14 (I believe it's available in stainless steel?).

In real life, I'm not sure how much stainless steel is in the average residence, but I'll bet that most kitchens have stainless steel sinks, faucets and a lot of cutlery...

Salvaging stainless steel for the Kentucky Free State could be a relatively easy and profitable operation. The stuff survives fires and (allegedly) doesn't rust. The ruins of an apartment block would be equivalent to a "stainless steel mine"

The KFS is a trading nation. Merchants from anywhere along the Mississippi will happily sell stuff obtained from the ruins: scrap metal, old tires and plastic materials in exchange for "moderate-tech" manufactured goods and pharmaceuticals

The KFS is an industrial nation that has no shortage of energy. They can burn coal or renewable fuels or they can use the fusion designs they've stolen from the Morrow Project.