I have a weird issue where my companions won't use any weapons i give them without ammo, yet if they pick a weapon up they will start using it for a while with no need for ammo. Then when i do give them ammo it disappears within minutes. I gave thousands of 5.56 rounds and they just disappeared, it's not possible to have fired that many shots in 5 mins.

Im wondering whats up with this? i thought companions would not need ammo, if they do it makes it kinda ridiculous trying to give them interesting weapons, because i myself struggle to have enough ammo unless i swap between 5 different types at any time.

Companions only have infinite ammo with their base weapon.

Any gun you give them requires ammo. You also have to equip the gun on them.

The reason they pick up a gun and immediately use it is because when you pick up a weapon, it has ammo in the magazine.

Companions seem to loot weapons from bodies and use them temporarily with a limited supply of ammo (presumably from the body they looted it from).

This mechanic slightly intrigues me. I like it though, because they hoard weapons they pick up even if they ran out of ammo (and when you have the scrapping perk, hoarding weapons = LOTS O JUNK!).

One thing I dont understand is how they find the ammo. Im extremely disciplined with looting EVERY single body for ammo (i dont take the weapons usually, but the ammo yes, even if its .38 for which I have no use of). I ALWAYS take all the ammo from bodies so I wonder how the hell they find ammo for the weapons they loot.

Is ammo in the magazine able to be traded with? Or is it counted as part of the weapon? Becuase when I notice my companion holding up a presumably looted weapon, I activate a trade and I do see ammunition equipped that I can take away.

I just want to mount a fat man to dogmeats back...

Well the companion i was using was Curie who seems to have no default weapon.

Makes it pretty annoying because she uses melee most of the time.

In previous games, when an NPC picked up a weapon, the game automagically added a small amount of ammo for the weapon to their inventory. Since NPCs didn't use ammo, a few rounds in their inventory was all that was needed to let them fire the gun indefinitely. This also allowed the player to pick up some ammo for the weapon, as well. In fact, there was actually an exploit in previous games that took advantage of this to get more rounds of Alien Power Cells: kill someone, place the Alien Blaster and a single APC on their corpse, then wait for another enemy to pick it up. Kill them, repeat for another enemies, then collect APCs from the corpses of everyone who had picked the weapon up. You'd end up with more than the single APC you'd put on the original body. I don't know if the same thing happens in this game with NPCs, but when you pick up a weapon, you do get a decent supply of ammo for that weapon. I tested this with the Minigun in USAF Olivia: checked my 5mm rounds before and after picking up the Minigun off the named raider there, and saw an increase in the number of 5mm rounds in my inventory. And I made sure to check before picking up the Minigun, and after, not after looting the entire corpse, so I know it was from the Minigun, and not the rest of the ammo on the raider's corpse.

Any ammo in a guns mag is automatically extracted and put in your ammo tab when you pick it up, whether from the ground, enemy loot tables, companions, etc.

Curie before or after her transformation? If before, well she is a mr.handy and her default weapon is a laser like all MHs. if after, well then yeah likely an oversight by Beth not assigning her a new default after the switch.

Companions are tanks for me. So I just give them a melee weapon then they loot whatever weapon. I equip them with Ripper, send them in the danger zone, then I crouch and sneak attack with VATS from a distance with Righteous Authority. Level 36 NInja VATS Rifleman build.