FN FAL Gas adjustment and gas system explained, gas tube removed

How to adjust gas system on any FN FAL rifles? Real life, real demonstration with different kind of ammos, steel cased and brass cased as well.
Plus a neat trick in case of a stuck empty case: remove magazine, place your hand (palm) on the charging handle, and smack the rifle butt against a table, bench etc (not concrete...), just don't hammer the charging handle, you can break it off easily. The inertia of the rifle's weight will solve your problem. Even a rubber mallot can break of the handle, it is a rigid metal.