First the you want to do is go into first person if your in third person. Next go behind cover aim down sights and hold the first/third button. Now let go of the button you aim with while still holding the button that toggles first/third person view. After that let go of the first/third button and go wherever you want. When you want to come back just hit the first/third person button and it will send you back to where you first took cover.