Double-barreled flintlock turnover pistol, Michel de la Pierre (attributed to), 1645 - 1650
The turnover system allowed a barrel, after having fired the first shot, to be turned rapidly over its length for a second discharge from the other barrel. It required just one flintlock and was therefore cheaper than the system employed by superimposed pistols, whose two barrels, one on top of the other, each required its own flintlock.