Just doing some more testing with this in the firing range. The stutters get better or worse depending on FPS.
125 FPS limit in game - mouse movement is smooth.
Here is the interesting part. Increasing or decreasing the FPS limit +/-10 FPS causes the stuttering to return. So at 115 FPS and 135 FPS.
I'm not really sure what to make of that, but it seems the game has some fixed interval for mouse polling and the father away the FPS deviates, the more apparent the stuttering becomes.
BF6 forces a system-wide polling rate of 125hz on every input device. That's why your experience may feel smoother. However there's a bug with that too, and it will stutter 3-4x a match, 30s intervals.
DrTH1CK Okinouko, tested BF6's polling rate with MouseTester
PSA: Mouse Input is broken in this game looks similar to bad frame timing | EA Forums - 12734467
8ms polling = 125Hz
1000ms ÷ 8ms = 125Hz
