In short
Every scope has a default reticle. If you really dislike the default reticle, and are too lazy to visit a workbench and change it, then this article is for you. This article will explain how to modify the default reticles of any weapon.
NOTE: The framework is required.

Before you start
- Make sure you have the framework installed.
- Make sure you know where you Fallout 4 Data folder is.
- Determine of which weapon you want to edit the default reticle.
- Determine which kind of reticle and dot you want.

Changing the Default Reticle
First of all, open the explorer, and navigate to your Fallout 4 Data folder.
Next, go to the following folder:
Materials > Scope
In this folder there will be a bunch of folder named after weapons, for instance '10mm' and '44'.
Some weapons share the same default reticle, like the Combat Rifle and Combat Shotgun for instance.
The mapping of these folder names to the various weapons is as follows:

Weapon                        | Folder Name
----------------------------------------------------------------
.44 Magnum   | 44
10mm Pistol  | 10mm
Alien Blaster  | AlienBlaster
Assault Rifle  | MachineGun
Combat Rifle | CombatRifle
Combat Shotgun    | CombatRifle
Deliverer       | Deliverer
Hunting Rifle | HuntingRifle
Institute Laser       | InstitueLaser
Laser Gun      | LaserRifle
Laser Musket  | LaserMusket
Plasma Rifle  | Plasma
All Recon Scopes    | ReconScope

Below these folders is a list of Material files. These files 'contain' the different crosshairs and dots that are available.
Now to actually replace the default reticle of weapon X, you need to do the following:
- Select both a Crosshair and a dot from the materials. A crosshair has the prefix ReticleCross and a dot has the prefix ReticleDot. If you do not want a crosshair or dot in your default reticle, select the ReticleCrossEmpty or ReticleDotEmpty files.
- Copy the selected files to the folder of weapon X. 
  We will call these files ReticleCrossYourChoice and ReticleDotYourChoice from now on.
- Now there should be four files in this folder:
   > ReticleCrossDefault.BGSM.BGEM
   > ReticleDotDefault.BGSM.BGEM
   > ReticleCrossYourChoice.BGSM.BGEM
   > ReticleDotYourChoice.BGSM.BGEM
  It is possible that the last part, .BGEM is missing. This is not an issue.
  Delete the ReticleCrossDefault and ReticleDotDefault files.
  Now do the following if the .BGEM part is missing:
     Rename your crosshair file to ReticleCrossDefault.BGSM
     Rename your dot file to ReticleDotDefault.BGSM
  Otherwise, if the .BGEM is NOT missing:
     Rename your crosshair file to ReticleCrossDefault.BGSM.BGEM
     Rename your dot file to ReticleDotDefault.BGSM.BGEM
     In other words, make sure the file has the extension .BGEM.

That's it! You are all done. Weapon X now has your own custom reticle.