Call of Chernobyl is a free-play sandbox mod for S.T.A.L.K.E.R. : Call of Pripyat created by TeamEPIC. It features 32 explorable maps, reworked level design and level fixes, new original level, Trucks Cemetery, Full AI and A-Life overhaul, engine and script enhancements, Repeatable task system which bases itself on A-Life events, Customizable weather environments for every map as well as surges and psi-storms from AF3, Character creation which includes name, portrait and faction selection; Several optional modes such as Ironman mode, story mode and zombie survival mode, New achievements, rankings and reputation system, PDA leaderboard and enhanced PDA statistics, Companion system with keyboard issued commands, many optional side-features and community-made addons . Call of Chernobyl was player's choice Mod of the Year 9th place in 2015 and 1st place in 2016!
This mod brings back good old sounds of vanilla weapons and grenades from SHOC to CoC, making them feel more powerful (at least in my opinion).
The mod is made by WojachPL and not me, I just uploaded it here because I'm sure there are many people who didn't search for a mod like that and didn't know it even existed.
The mod works with vanilla weapons for both 1.4.22 and 1.5 versions of CoC, not sure about OWR but it could work too, I suppose.
Open, drag and drop into your CoC folder just like any mod, simple.