Why have rifle grenades fallen out of popularity in modern arsenals? Their main disadvantage over 40mm grenades is that they have poorer accuracy, but surely RGs could replace hand grenades carried by soldiers, whilst retaining the option of also carrying dedicated 40mm grenade launchers? As RGs don't have spent casings compared to 40mm grenades, they should also be lighter for the infantryman (i.e. better explosive payload:encumbrance ratio) There are already RGs out there that don't need a blank to fire based on the 'bullet trap' system, e.g. the Israeli "Simon" door breach grenade. So it shouldn't be an issue that soldiers need to fiddle with blank cartridges to fire their RGs.