Connected too this question: Possible propellants more potent then gunpowder (16th-17th century)
The Sanguine King wishes to build a Grand Bombard unlike any other. For this purpose he needs his finest metal workers to build not only the largest cannon, but also a stable one citing the death of his ancestor Alphonse the Enlightened's death by a cannon he was viewing as a unfortunate and hopefully unique accident for his household.
In this world guncotton was discovered much earlier meaning you have a more powerful propellant for any cannon ball or projectile. If that would limit cannon size.
if any techniques or processes could have the possibility of being discovered earlier in our world you can use them in your answer.
I don't know which measurement to use for size. I would prefer caliber, barrel length, and maybe a really rough estimate for weight.