Hi Alexander, and welcome back!
Thank you so much for posting this highly important drawing, you did a tremendous work!
I must admit that I did not know the manuscripts of Lorenzo Ghiberti, so - wow!
Most interesting is the fact that Ghiberti died in 1455 at the age of 70. As the breech loading gun he illustrated is almost identical in all its features to the actual piece that I posted here this could mean that the gun is even older than I thought it was and it should be probably dated at least as early as the 1450's!
I am also fascinated to see what the original tiller stock looked like and that not all of them were just plain sticks.
For easier comparison I repost the images of the gun together with Ghiberti's drawings and would be grateful for any incoming comment.
I also attach a portrait of the artist Ghiberti.
Alexander, thank you again for adding valuable material to our discussions once more!
Best wishes go to Russia from Bavaria,
Michael