The hip fire from Saritch 308 is like a beam. It doesn't spread like the other weapons. People expect it to work like M4 Carbine/HK416 but it doesn't. When you're moving and jumping your aim is off. That being said, yes there are hit reg issues even with M16A, whether aimed or hipfire. I experience it the most when I have my work VPN enabled. People have told me that I was just standing there or hopping round when infact I had emptied a clip.
Your router, your PC, your ISP everything plays a role. If you want close to 100% hit detection move to Canada, next to the server room. I often lose to low pingers in close combat, I have to anticipate their movement to adjust my hit registration, lack thereof, miss offset.