I found 2 bugs, shown in this short video
Hit registration - as you can see in video, I guessed might be other player (the one I shooting at) are high ping or lost connection, sadly I forgot to press Tab to check his ping but my ping is normal (see in-game stat top-left of video)
Or might be server just lag spike, but I shooting more than 10 second hit still not registering.
This bug rarely occurred, but it do happened again, not just 1 time off
Floating Magazine - see in the end of video when I sprint, happen all the time in other situation too (e.g. change primary to secondary weapon)
my setting : everything Low or off when possible, except AA and Ragdoll count = medium