With the M14 it's the easiest to reproduce. Simply take out the magazine, shoot the round in the chamber, then reinsert the magazine and watch the bolt teleport into the open position for the animation.
With the other 2 you have to engage the safety once after the round in the chamber has been fired, which makes the bolt magically snap forward without a sound or proper animation. If you then reload, you will also have the issue of the bolt teleporting to the open position for the reload.
(If you shoot the last round without a magazine, bolt hold-open isn't engaged which automatically leaves the bolt closed. To do this with a magazine inserted, engage the safety once.)