great bottle cleaning tip for stuff that hardened inside the bottle

My father told me to get some shot (bbs). when cleaning the bottles everyone has run into that little bit of dried stuff in the bottle the brush cant reach. put the shot in the bottle with water (cleaning solution) and start swirling. It works great. It even works on the gallon jugs for the stuff around the neck. Im just trying to give back for all the info you all have given me. Stephen