Earlier today I was set upon by a zombie, and did not have time to switch weapons, so I shot him with my M4. He died (or at least, seemed to on my end) immediately, then a couple of seconds later there was a bullet ricochet noise by my right ear. After diving for cover and scouring the area, I checked the player list. No one was online, so I suspected a combat logger, but my Desync value was >0. (Approximately 45 if I remember correctly)

Later on, I shot another zombie and this time, after a second or two of me running, there was a ricochet noise again and this time I noticed the little puff of dust as the bullet hit the road as well. This lined up with the shot I had taken, but I only noticed afterwards, heart attack moment and all that. There were 2 others online this time but again, I had a desync value of >0.

Also, I suspect that much earlier in the day I died to my own axe blow, as I killed a zombie, stepped forward and died of seemingly nothing, but I have no evidence on that one, so I may be wrong.