When running with weapon in ready position i.e. when run key is released weapon will raise but because you are currently running it is down

holding freelook key does not allow full freelook but rather activates free aim

-------

A second explanation for clarity;

when you have your weapon up ie looking down sights, and hold freelook, it enables around 30 degrees of horizontal aim which snaps back to the original aimpoint when freelook button (left alt) is released

right click to raise ironsights, then hold shift and run. weapon adopts down, ready, running position ie ironsights are not up whilst running, but the 30 degree limit is still active even though you are not actually looking down the sights

---------

names for clarity - 30 degree horizontal freelook