I would guess that its very unlikely to not have all 3 chambers to fire simulaniously as they are connected with an 1" hole , especially since they used lose powder when loading the barrels .
there is no multipple "vents" , its not easy to detect on the drawing , but if you look closely at the breach photo of the drawing you can see that there is only one vent for the center bore .
and if you look at the photo of the barrel you see it clearly with only one vent .
but ok there is probably an reason to why this wasnt an common used and produced cannon model ,
could have been accidents or difficulties to produce them . I dont know why .
I only know that I love the design both of the barrels and the sledges .
an 1:3 scale model of the barrel would be approximately 18 - 19 inch long
maybe 3 feet total length mounted on an slege
a bit to big to be used as an desktop model , if you not got an large desk
,
but it would sure look good to have one in the office ,
in the livingroom it would be nice to have one in full scale
but if by any reason one of the bores would fail to ignite it would probably destroy the wall between the bores .its way to thin to handle the pressure . but who knows ?? I for sure dont , this is just my personal guesses .
but ok we cant know for sure as long as we havent tested it . its only in the exact bore center you have that very thin wall , move 1/4" up or down from bore center and you have rapidly increased the bore walls to an acceptable wall thickness .
but if we try to think logical its to thin in the center area , but as its circular on both sides it will help to deliver the forces into different directions there its more material . its difficult to try to explain how Im thinking as Im not an native english speaking person .
its the same as when you build an bridge , you use a lot of triangular shapes to spread the force .
I must say that this is way over my level of knowledge to try to discuss this matter , sorry
both because of lack of knowledges of the english language and my limited knowledge in this matter of calculating powers , forces and material strengths .
hope there are someone at this forum with some more intellect and education then me who can help me with this . it sure would be nice to know .