These questions are some that I ran into too while learning the mod, since the documentation is a bit thin (at least non-video documentation), and even then it's a little nebulous. If someone else has more info, or I've said something wrong here, feel free to correct me. Squib ratio is the maximum amount of barrels an assembled cannon can have per charge/chamber block for it to be safe, or how many barrels you should have at minimum to keep the cannon from exploding. (pondering a gunpowder charge will reveal this too) The "regular" cannon ends you're talking about can't be opened at all; Cannons that use them (cast iron and forged iron only, I think) are muzzleloaders, meaning you have to load the round in from the front. Thick and built-up are for aesthetic, I believe. I know when I built my test cannons (in creative), I used all thicknesses to give the cannon a more realistic bevel. It's possible that the creator intends to make them more useful later, but for now, I don't think that they offer any utility. Some other things to note while making these cannons that I wish I knew earlier: Assembled cannons will explode if you attempt to fire them while the cannon's chamber or barrel is clipping through another solid object, and cannon strength is a soft cap, not a hard cap. A cannon built to handle more charges than a cannon's strength value might not explode when you test fire it, but is still unsafe. Edit: incorrect terminology, as pointed out by califour below. Answer from Pvt_Murphys on reddit.com