Installation ver. 2.0:

If you're completely new to install mods follow this brief wiki guide http://wiki.tesnexus.com/index.php/Fallout_4_Mod_Installation 

Then download and install DOOMBASED's M1911 Standalone Gun: 
extract "Data" folder inside "Fallout 4" folder in "yourgameinstallationletter*/ProgramFiles/SteamLibrary/Steamapps/Common/"

Now download and install this mod: 
extract "Data" folder inside "Fallout 4" folder in "yourgameinstallationletter*/ProgramFiles/SteamLibrary/Steamapps/Common/" SAY YES TO OVERWRITE ALL

Both main file and optional file have all the files necessary, only Main file has the alternative sound in addition, so you have only to download the one you want.


Uninstallation ver 2.0:

Go into "yourgameinstallationletter*/ProgramFiles/SteamLibrary/Steamapps/Common/Fallout 4/Data" and delete "1911" folder respectively in "textures/weapons/DOOM" and in "sound/FX/wpn/DOOM".


Credits:

DOOMBASED - Original "M1911 standalone gun" Mod

Hector Shiroi - Classical Colt 1911 A1 Mod (complete retext, mesh edits, sounds)

NB: If you want to use my work ask first!