The weapons have such high damage because the aim of this mod is to bring realistic weapons into the world of Fallout. Along with realistic weapons, comes realistic damage.
If the damage is too much, please consider using the MCM Menu or Settings Holotape, both introduced in 2.6.1, to reduce the damage to a level you feel comfortable with.
If you are an Xbox user on 2.4 or 2.5-1.4, a search on BethNet should get results for Xbox damage patches from
Dukman for 2.5-x.x & from
Wolfdie for 2.4 & under.