The issues mainly affect weapons with internal magazines; they shaking strangely in the hands when loading/unloading.

The screen also jumps strangely when reloading after a shot (while aiming down the sights).

Sometimes the repeater is positioned incorrectly in the hands (though I haven't really checked other weapons closely).

I should add that I'm playing on my own private server and this problem exists even without mods.

reloading, loading, and unloading a weapon