You can acquire this mod by going to nexusmods and you will need harpoon ammo as you will need to find it. This secret weapon can only be modded by PC gamer and unfortunateally console gamers will not be able to acquire this great secret weapon. This secret weapon needs to be crafted and will provide you with the location to all the necessary items that you need to locate and create this crafting of this weapon. In this Fallout 4 guide will provide you with a location to a secret weapon that you can find in the game.
Fallout 4 Railway Rifle Secret Weapon Location