Note: If a Compensator and Bayonet are both attached at the same time and the user attempts to switch out the Compensator for another one, it will delete the Compensator.
Thanks to Magicks for finding this out.
What Magicks said: "Also if you have both bayonet and compensator attached (after you do it in the correct order that lets you have both attached) and you try to switch out your current compensator with another it will put the old one in your inventory, and completely delete the new one you were trying to put on. It doesn't drop it to floor and take awhile to reappear, it doesnt drop it threw the floor to another level. It just disappears."