Where can I find some 12.7mm ammunition? The only place I've found that has it so far is the Brotherhood at Hidden Vale, and they only have a small number.

Also, can I make AP rounds? I have the handloader perk and a repair skill of 75, but I don't see the option to make any AP rounds. Do I need to learn a recipe or is it not possible to make AP rounds? If I need a recipe, where do I find it?