Why is this video even going round? 
@Fragmented_Wolf
The Kill Cam shows the server’s view, which has been inaccurate since the Tech Test [Confirmed here]. Due to Gear’s fast gameplay, and the lag compensation, the Kill Cam doesn’t show what happens accurately, that’s the only thing your video demonstrates. Seen in the pictures below (tried my hardest to pause at the correct times):
By looking at the hit marker detection and the animations you can see how the perspectives line up. So if you put these pictures on top of each other the recticle for the Kill-Cam would line up on the T-800’s head in the killer’s perspective.
Just to further explain. In this picture you have fired the shot and your reticle is over their head, but there is no hitmarker yet.
Also, this video is demonstrated with a Longshot, a precision weapon where aim-assist is even more prominent and the majority of the issues people see are with the Gnasher, so can this video even be taken seriously? Lol.
Furthermore, I personally ignore situations where there is a very small distance between the recticle and target. But now, take a clip like this [Video Link], where the enemy is still stunned while I am halfway through the roll animation, from both perspectives. I am also on his left side so the ‘gun triangle’ has no effect and the player himself only turns to follow my character after his shot is fired, not a consistent ‘sweeping’ movement like in the OP’s clip. It’s also a blindfire shot while I am next to him in both perspectives (pause if you need too) and he lands a full spread and gets the kill… in this situation I would have expected maybe half a spread due to lag compensation, but to get the kill… really?
Situations like these don’t even make me mad, they’re just shocking to see and the fact that people play it down to kill-cam latency is disturbing. Unfortunately, I don’t have the killer’s perspective to analyse, which would have been helpful. Maybe there is an issue between the hit detection/hitbox when rolling - who knows.
TC have definitely messed around with the aim-assist in Gears 5, it is blatantly obvious throughout Arcade and the easier difficulties. But you need a keen eye to catch it in Ranked gamemodes, other than Escalation and Execution where it doesn’t cause issues. You can only see it while you’re in control not on a kill-cam or a video, because no one can make the distiction between the aim assist and your movement with the controller.
Lastly, the majority of my issues are when me and another player are in close proximity, which leads me to believe that the Gnasher’s Up-Close aim-assist is what is creating issues. This is what Gears 4’s up-close aim-assist is:
If you are experiencing issues, were these instances in close proximity or not? It would be interesting to find out from others.