Has any arm of any nation ever used small calibres in the field? I am very surprised that .22 has never found its way into a suppressive fire role. Especially before the days of body armour and in urban warfare. Would you poke your head round the corner if hundreds of .22 rounds were splatting against walls and windowsills. .22 can kill or seriously hurt you for the fraction of the cost/weight/size requirements of .303/7.62/5.56 ammo. Although it would be no good as a main assault weapon or over long distances, a few automatic 500 round belt fed .22 per company in urban warfare environments would be a pain in the ass for suppressed enemy infantry. I would not be surprised if this had already tried this in the past? If not why not?