I've crafted 42T's and only got them to 125/100 dura. I'm not sure what the mechanics are for the badge, but I'm sure it's not the level and size of the cannons.
After you reach level 10 crafting, any extra crafting you do improves the durability of the cannons, think of it as crafting level 11 to 20, Once you reach "crafting 11" your lowest sized cannon has a guaranteed 400 durability and so forth.
Once you reach "crafting 20" the biggest size cannon and every cannon beneath it will be 400 dura.
Note : There is no crafting levels further than 10, I just used them to give an easy explanation.