Most custom skins work on public servers, but some competitive "Classic" servers or leagues (like ESEA or FaceIt, if still active for 1.6) may enforce sv_pure 1 , which blocks custom models to prevent cheating.
You will usually get a .zip or .rar file containing .mdl files (e.g., v_m249.mdl , p_m249.mdl , w_m249.mdl ). Locate Your Game Folder: cs 1.6 m249 skins
: Many players sought skins that made the chunky M249 look more modern. They would download "HD" models featuring realistic textures, tactical railings, and sharper reloading animations. The Heavyweight’s Wardrobe: A Deep Dive into CS 1
No. Valve will not revisit the 2003 codebase. However, the unofficial legacy is richer than any official release could have been. CS2 (M249 | Spectre, M249 | Nebula Crusader):