Grab all the weapons you can and sell them to 🏡 after repairing them (jury rigging helps). Buy out ammo types you use, similar ones or casings/powders/primers. Use the hand loader perk to mulch similar ammos and re-craft them into what you want (anything that’s a straight damage boost that isn’t JHP is good; don’t bother not buying special ammo types, there’s no real point for the most part except for the occasional armor piercing or explosive 50; maybe hollow points if you know what you’re fighting won’t have DT).
If you’re worried about ammo? Take vigilant ammo and don’t worry – HOUSE will puke ammo at you.
For explosives, just buy it.