So apparently small-scaled cannons explode when fired. I can't pinpoint exactly at which scale the cannon will start to explode, because base length and barrel length both impact how this bug triggers. But from my experience, the cannon explodes at base length 70% and barrel length 60%. Here's a test build to demonstrate the bug. Video demonstration.
From my experience this usually happens when you scale the cannon smaller and the full-sized shell impact something on its way out...
Idk I managed to use a cannon with super high ROF and a diameter of 0.01
@jamesPLANESii Thanks.
@MrVaultech Yes, disabling collision does fix it. But it is still a bug that needs to be fixed by the devs themselves.
From my experience I believe its because the shells impact from the fire rate when that small, so setting the cannon to "no collision" fixes it.
Post your bug reports here