First download:
https://www.gtainside.com/en/sanandreas/mods/151956-end-of-the-line-cutscene-weapons-fix/

Replace modded original Riot_4d.ifp and riot_4d.cut, If you installed that mod. If you didn't installed yet. Just add csak47 and replace riot_4c.ifp, riot_4c.cut files.
Muzzleflash Particle Effect Fixed.