I have played around with this issue as well but have noticed something, by using the Space Bar, u can raise or lower your Rifle or compass. if in your case u hit the Space Bar to raise the Compass when u switch to another Item it will make u stop but if u hit the Space Bar to lower the Compass then Switch to another item the action will NOT stop your Character's movement. Same applies to a weapon. Feel free to test this for your self to see the outcome.

Here is a video showing the bug:
http://youtu.be/nv2INsVgp0Q