> An engine requires piston that move within a bore. To create the pressure that process has to be precise. This process was perfected in making cannons.

There is speculation that the techniques for casting these cannons, was actually perfected in making church bells. Basically, if you turn a church bell on its side you have a primitive cannon. This may be one of the reasons that Europe was able to harness gunpowder more effectively and climb to dominance.