Complex sentence: A repeating rifle is a single-barreled rifle containing multiple rounds of ammunition which are loaded into the gun's chamber from a magazine by means of either a manual or automatic mechanism, and the act of loading the rifle typically also recocks the firing action.
Split into simpler sentences: A repeating rifle is a single barreled rifle containing multiple rounds of ammunition. These rounds are loaded from a magazine by means of a manual or automatic mechanism, and the action that reloads the rifle also typically recocks the firing action.