There is an optional version that works in the same way, but has the addition of +2% damage for guns per rank of gun nut.
By itself this mod does not do anything, but instead is meant to be used with other mods. Basically if more than one mod implemented their own 5th rank to the gun nut perk, then the mods would conflict, and one would probably not work.
To help prevent possible future conflicts, if anyone is making a mod where they would need a 5th rank to the gun nut perk, then they should use this mod as a parent to their mod. If a modder needs more ranks beyond 5, then they should modify this mod as to keep the perk IDs the same and the file name needs to remain the same. No permission need to make and distribute your own version.
To find out the ID of the perk use console command:
help "gun nut" 4
It should be the fifth entry starting with "Perk:" and the ID should end with 812