Hi Michael,
Thank you for your kindness in including me in this category, which though I am not actually one, I am always honored to be in the company of the many here who are.
My first instinct in looking at this thing is....what the heck were they smokin' in those days!
It is interesting that this interesting...actually bizarre....illustration is contemporary with DaVinci, and many of the inventions he put to paper were probably considered equally bizarre in those times. Surprisingly, a number of them truly did come to fruition....thankfully this guys idea did not!
I cannot imagine how such a firearms nightmare could ever have been actually conceived as a viable invention. I cannot help but think that this illustration may have had some allegorical intent, much as Fearn has suggested. I think his points on the improbability of the dynamics of this 'invention' are well placed also, as perceived by my own very lay understanding of technical things.
It is known that many famed classical artists in these times, with DaVinci at the fore, often had unusually wry and profound symbolism and mysterious satire imbued in thier works . Naturally the pretense of "The DaVinci Code" strongly suggests this somewhat plausible potential, regardless of obvious conflicting perspectives.
As we have discussed before with multibarreled firearms in developing times, there was a distinct problem with simultaneous ignition. In many cases, from what I understand, guns such as the 'pepperbox' pistol, with six or more shots in a revolving chamber, could easily discharge all at once...probably not good for the firer of the weapon !
Fernando, interesting note about Leonardo's invention of the pointed projectile, as I always say, amazing what you have in that archives of esoterica!
All the best,
Jim