you know ping is the often reason for laggy bullets right?
also i will admit they messed up the hitboxes, but there is a fix which i implemented, now its like 5 bullets.
also it may be your gun. my AN-94 takes five shots to kill someone. but the AEK971 and the XM8 take a lot longer to kill someone due to low damage.
plus in the latest patch they increased damage for assault rifles.