All credit for this guide goes to SnowNinjaRaccoon (DK) & PowerPyx from PowerPyx.com who provide a complete guide to finding all collectibles and all weapons in Vampyr.
This guide covers all 11 ranged weapons in chapter order, although the guide they created also covers all collectibles and melee weapons as well.
Prologue:[Ranged Weapon #1] Used Revolver
Granted automatically in your shelter at the beginning of the game (upper floor).
Chapter 1:[Ranged Weapon #2] Used Lupara
After the bar, the boat corpse and switching to other side of the docks. In a chest on the second floor of the second warehouse you will go through.
Chapter 2:None
Chapter 3:[Ranged Weapon #3] Common Pistol Parabellum
Granted for defeating Jimmy “The Spark” boss fight. (Flamethrower guy in the docks, forced fight).
Chapter 4:[Ranged Weapon #4] Remarkable Pump Action Shotgun
While investigating the source of epidemy in West End, you will find it in the eastern house you will have to visit.
Chapter 5:[Ranged Weapon #5] Good double-barrelled
2nd floor of the shopping mall in the north of West-End district. You must defeat the enemies here and then teleport upstairs to the chocolate store on 2nd floor (you will go through the shopping mall during the story on your way to the park).
Chapter 6: Important: Make a manual Save Game Backup at the start of Chapter 6! See spoiler:
*** Spoiler - click to reveal ***Many weapons are from embracing different citizens so if you’re on your Pacifist run for trophy “Not even once” it is important you keep a backup save from before embracing anyone (killing people also voids side quests)!!!
After beating Chapter 6 there’s no way to go back (you would have to start a new game and lose all your progress). The Harriet Boss Fight is the point of no return, when this fight triggers is the last chance to go back. In Chapter 6 you can still free-roam and revisit places.
PS4 Backup: Go to PS4 Settings > Application Saved Data Management > Saved Data in System Storage > Copy to USB Storage (if you back up to PS+ Cloud be sure to disable Auto-Upload or else it will overwrite your save).
Xbox One Backup: Quit the game at the start of Chapter 6 to trigger the automatic cloud upload > (double-check that it really uploaded to the cloud) > go offline (pull the cable or disconnect from internet in console settings) > kill everyone for their collectibles > delete your local gamesave > go online again to automatically re-download your cloud-save and continue with the other path normally.
[Ranged Weapon #6] Milton’s Shotgun
Embrace Milton at the Pembroke Hospital (alternatively, it can also be bought from him).
[Ranged Weapon #7] Clarence’s Parabellum
Embrace Clarence in West End.
[Ranged Weapon #8] Joe’s Semi-automatic Pistol
Embrace Joe’s son Harry Peterson in Whitechapel.
[Ranged Weapon #9] Albert’s Revolver
Embrace Albert Palmer in Whitechapel.
[Ranged Weapon #10] Edwinas Double-Barrelled
Embrace Edwina in the Docks.
[Ranged Weapon #11] Tom’s Revolver
Embrace Tom in the Docks.