do you also need to give them ammo for that weapon?

yes

Well you don't absolutely need to, they just won't be able to actually do anything useful with it

They have a default weapon that never runs out of ammo, otherwise they use it up (rather quickly if it's an auto) same as you would and can't do much with it when out

that makes sense whenn i think about it.

otherwise you might have a preston with fatman+unlimited ammo for it... and massive issues thereafter. lol

Does anyone know if settlers work the same? I like to give them something better than a pipe pistol. I give them some ammo, but the ones who go to other settlements I am now worrying about. I have no idea if they used up their ammo.

same aswel

hell, i dont even know how to locate them. short of attempting to follow the same route they do. :/

not an ideal user interface in this game for managing some of these new game additions.

Well I did find an legendary "Neverending" pipe autorifle that had unlimited ammo it never had to reload.... To bad the damage was only like 10. Now the quest for the Neverending Minigun begins.