Got a Real-World Weapon, Armour or Tactics Question? Mk. XXX

[stoutstien]

A question about guns: What's the relationship between barrel width and weight?

I'm trying to write a system that allows for flexible gun customization. When I look at example real-world guns, it seems like barrel widths from 5mm (.22 cal) to 20mm (12 gauge) weight about the same, but as soon as you go to 25mm everything gets much, much heavier.

Is there some extreme nonlinearity? If so, why are 150mm guns mobile with small teams of oxen?

Is it that anyone who bothers to make a 25mm gun adds other heavy features? If so, what?

Thanks from a gun newb

Max chamber pressure and heat displacement is more important than caliber when you are looking at wall thickness. That's why shotguns can have thinner barrels. Even the punt guns which could have a 10+ ft barrel only clocked in at around 100 lbs even they they threw over a pound of lead in a shell because they had low pressures to deal with.

Lobbing gobs of material over great distances from a dead stop means you need a lot of pressure. Cast iron cannons were prone to failure due to both the heat and pressure making or finding weak points. modern artillery is meant for frequent use so it's built to eat it in strides. You don't get that without mass. Heat is also an issue if you don't sink it away. See cooking off and thin/light walled larger caliber option such as leather cannons.