Fl4k Crit Build not working in Online Multiplayer

This Build does not work in online multiplayer, but it works flawlessly in singleplayer mode.

It seems the hits Register to late, im always reloading, and this is wrong. I think it has something to do with hit detection and the lag in multiplayer.

Anyone else with this Problem? its pretty bad, cause the whole build is not working in online, that sukks ,)