I understand what you are trying to do, but it would be pretty hard to call the Puckle a "machinegun" in any modern sense of rapid fire.
The operator turned a handcrank to move the cylinder back, turned the cylinder so a chamber aligned with the barrel, then tightened the crank to push the front of the chamber into the end of the barrel (sort of like a Nagant revolver). After firing that chamber, the crank was wound backward to pull back the cylinder, so it could be turned, aligned and again tightened. Rapid fire for the time, yes. A machinegun? Well, I don't think one would have to be registered with BATF.
Actually, had the inventor decided to forget the breech seal and just go with a turning cylinder like a modern revolver, the gun would have been much more practical and might just have taken off.
But yes, they were trying for rapid fire but the technology was not there yet. I have no doubt that George Washington would have loved to have had a few thousand M16's.
Jim