2.0 UPDATE: Dozens of new sounds sourced from BF1 and V for all impact sounds (courtesy of Xioranthha), completely reworked Dirt and Concrete sounds to get rid of the extra "crunchy" elements that sounded unrealistic, the results are very good
2.1: Reworked wood sound, extended fade out range curve so you can hear impacts from a bit further, added a couple dozen new sounds for cracks, power armour, and wood. Approaching perfection for the lower volume version


Load this mod as low as possible to avoid incompatibilities, it's very non-intrusive and can be put even dead last, I suggest you do it
I still suggest you use this mod in conjunction with mods that alter the vanilla soundscape, my personal recommendations would be:

MWGS for all the guns you can find
JSRS for all the guns that remain
R&A Overhaul with its fixes such as this or this or this (with all its extras)  
Simple Impact for extra beefiness
and my other mods, especially physics overhaul because it adds nice bullet casing sounds
Physics Impact Overhaul
Melee Impact Overhaul

Then, I highly suggest using mods that add penetration and ballistics (cough cough) , so that the impact sounds play as the bullet physically hits a surface instead of being an instantenous hitscan (further expanded in 1.3.1), and of course penetration is good so you have a damn reason to shoot at walls xD (unless you're magdumping)
Essentially: YOU NEED LOUD GUNS in order for this mod to truly shine, the vanilla sounds are a bit too low for the regular version, download the lowered sound version if you're in a vanilla soundscape


As stated this mod doesn't add any new sounds to the game (it now does), it only improves what is already present by modifying the sound descriptors of the vanilla audio files, as such it is partially compatible with mods like JSRS, I suggest putting this below all mods that affect bullet sounds and bullet impact sounds for a consistent soundscape

ESP marked as ESL, put below any sound overhaul that touches bullets in any way or you will have inconsistent results

The recently released Obscurum IV Overhaul by thumblesteen features a host of improvements and tweaks on the base game, but the one that left me the most impressed was his personal touch on a sound feature that has been mostly neglected in the FO4 modding space: bullet impact sounds! shooting a powerful shotgun with amazing sounds into a metal shack and only hearing a very timid "plin" always felt weird to me, this finally fixes that issue, and for all material types! concrete, metal, dirt, grass, water, flesh, armour. This touches every single bullet impact sound in the base game, without adding any new files, and overhauls them with pitch, volume and a custom sound model to make them sound freaking terrifying, you WILL duck when raiders are peppering you with automatic fire! I only took the changes the author made to selected sound descriptors, extrapolated them to a new esp (marked as ESL), did a couple tweaks myself and this is the result