This includes two experiences.

(server was medium full about 20 or so players for event night |"HIHBGaming.net (AU/NZ) - The Real Deal - 3rd Person Hive")

I was laying down behind a stone wall waiting for a friend, when another player ran directly over me, we both had AKM with drum clips, 3 meters between us, I got the jump first and fired my weapon.
I used 25 rounds until he "rag-dolled" and died, he managed to return fire but only hitting me in the arm, also spending roughly 20 rounds.

(server had about 5 players |"HIHBGaming.net (AU/NZ) - The Real Deal - 3rd Person Hive")

My friend was being chased by an infected and I told him to run straight so I could line up a clear shot, I missed a couple times and I couldn't see my bullets land elsewhere.
A second or so after I fired my suppressed M4, the infected took a hit and died.
My friend asked me if I was still shooting because he could hear my shots still ringing out although I had already fired my weapon.

We went into a barracks and I stood 3 meters from the wall and fired a round from my suppressed glock. It took 3 seconds between my gun firing and the projectile actually hitting the wall.
My friend saw otherwise, he saw me shoot 3 seconds after I fired my glock and the round hitting the wall normally.

I sometimes find when filling a vessel of water it just will not fill and I get stuck with cancel action.