MIRV Mod Swap Without Gun Nut or DLC (Fallout 4 Exploit) Walkthrough

MIRV Mod Swap Without Gun Nut or DLC (Fallout 4 Exploit)

Get and name weapons:
0 Pipe Bolt-Action Pistol
1 Missile Launcher
2 Fat Man
3 Weapon of Choice

Scrap and mod glitch:
Attach pistol barrel to rocket launcher
Attach rocket launcher barrel to fat man
Equip MIRV to fat man (Because "standard launcher" is now selectable)
Equip MIRV to any other weapon

This works basically because the bolt-action pistol is missing an attachment slot and putting its mod onto another weapon removes a mod option in the dialogue so you can glitch to what would be the third option down, allowing you to put the rocket launcher's barrel on the fat man....
This could be easier maybe or totally wrong, but idk. It works though.

This glitch is performed by selecting and scrapping weapons at the same time, allowing you to mix mods for different guns. Many explanations are available elsewhere.
I noted it in a Spiffing Brit video where he went through this laborious process involving the dlc to get a particular weapon that would accomplish basically this.