strangely enough, gunpowder, mre’s and sharpened metal will continue to work as advertised.
new york and the northeast corridor might turn into a headless chicken ranch... but other areas of the country will be fine.
In One Second Later one of the important barter tools was ammunition. Towards the end the going rate for a dead squirrel was five bullets -- a rabbit was worth 13. MRE's are good IF you can get to them or they can get to you and the military doesn't run out of them.