Another critical piece of overlooked knowledge is that the Founders didn’t need to “imagine” small arms more advanced than a musket, because they had already existed for well over a century. They were not yet cheap and durable enough for regular use during the Revolution, but any halfway intelligent person of the time—certainly genius inventor Benjamin Franklin—would have understood the inevitability of continued improvements and popular adoption.

 

Early grenade launchers and the first primitive revolver existed by 1600, and by the early 1700s the Kalthoff system (with later variations known as Lorenzoni and Cookson) had become fairly well-known. According to The Book of the Gun (pp. 229-230),

 

Successful systems definitely had developed by 1640, and within the next twenty years they had spread throughout most of Western Europe and even to Moscow. Thus, the inveterate London diarist, Samuel Pepys, could write in his entry for July 3, 1662, that he had examined ‘a gun to discharge seven times, the best of all devices I ever saw’…

 

A single forward-and-back movement [completes a process that] can all be done in one or two seconds, and the gun is ready to fire…and the number of charges in the magazines ran all the way from six or seven to thirty… 

 

About a hundred flintlock rifles of their pattern…are believed to have seen active service during the siege of Copenhagen in 1658, 1659, and again in the Scanian War of 1675-1679.

 

Notably, the system “found its way to America where records indicate that at least two New England gunsmiths actually manufactured such guns” by 1756, including one which “though loaded but once, yet was discharged eleven times following, with bullets, in the space of two minutes each of which went through a double door at fifty yards’ distance” (p. 232). Quite a few specimens of such firearms exist today.

 

In 1777, the Continental Congress authorized the manufacture of a “new improved gun” that was to “discharge eight rounds with once loading” and which the inventor claimed could be made “to discharge sixteen, or twenty, in sixteen, ten, or five seconds of time,” but the order was cancelled after he demanded “an extraordinary allowance.” 

 

By 1780, the Austrian army was using the Girandoni (sometimes spelled Girardoni) air rifle, early versions of which had existed since 1580. It could fire 22 shots in less than 30 seconds and be quickly reloaded up to four times on a single flask of air, with each projectile able to penetrate an inch of wood at 100 yards.

 

The 1790s saw the development of what might be considered the first machine gun, capable of firing 224 rounds at a rate of more than 100 per minute, with a 20-round-per-minute version directly promoted to George Washington. The pepperbox revolver, forerunner of the modern version, then came to prominence in the early 1800s. Several other multi-shot designs existed in the decades immediately before and after the 1791 ratification of the Second Amendment, but these are some of the most notable. The last of the Founders died in the mid-1830s, and there is no evidence that any of them (or anyone else) ever expressed concern that such firepower would continue to become more advanced and available to the general public.