Question

I apologize for posting this 'non-home built' question here.
But I believe here is where I am most likely to discover the answer.
My question involves how the Germans in WWII fired cannon through the
propeller hub of V-12 engines.
I cannot see how this is accomplished, since to my knowledge there were no
gear reduction units on these planes..
I can only suppose that the diameter of the 'throw' journal was large
enough,
that it always included the centerline of the crankshaft. This would be a
hugh diameter.
Thus a hole bored through the centerline of the crank,
would also be through each 'throw' journal. Thereby making a continous
bore,
with no exposure to the crankcase.
This seems unlikely, as it would add tremendous amount of weight to an
engine.
And, those ME-109 cranks I have seen on TV do not seem to have that feature.

So, I am still confused.
Again, sorry about posting here, and thanks.