Most of the rifles and the last shotgun or two are locked until later in the game, but since there's hardly any difference between them it's not a big deal. Except that sweet semi-auto shotgun.

I looked it up and made a big mistake with the fishing. It unlocks after you take Jack fishing. The way I remembered it, that was the last thing you did before moving camps. I've been avoiding that mission for a week or more and this whole time I could have been fishing.