For those of you looking for a Damage Upgrade Module (Ranged), I found one that is always there and respawns.
I haven't found a single post about this yet and I think a lot of people will want to find this specific module. Note: This requires the Terran Armada DLC.
Go to Niira in the Narion system. You will receive an emergency broadcast and start a quest called The Lost Terran. A new location on Niira will appear called the Scrapyard. You don't have to complete the quest for the module but when you land in the open area, near Buck-E there will be a ramp leading to a shed with some kind of power generator in it. On the table inside is the module. It respawns every 7 days so sleep somewhere else to respawn it.
If you complete the quest associated with the Scrapyard, after 7 days, all the stuff in Buck-E's workshop will respawn to loot without stealing and a bunch of terrans will respawn outside to loot and kill.
Buck-E will also give you a discount on installing weapon upgrade modules and weapon exotic effects.
Edit2: as u/gypsy_danger007 pointed out there is also one in the Va'ruun embassy storeroom in New atlantis. The key is near the ambassador. This one takes a bit more effort to get as it is locked behind the UC vangaurd questline.
Edit: fixed error