Fair enough, but keep in mind, a 2.5" piston is around 5 square inches of surface area on the face. Even at 10 psi of steam, that is 50 pounds of force moving the piston back and forth. The steam has no trouble moving the piston, especially hot and with some lubrication.
I was just wondering, I had never heard of purposely removing the tension of piston rings. On the car side of things we have to watch the amount of superheat to avoid damaging the rings (overheating and losing their tension). Because when that happens, the steam goes right past the piston and no work out of it - it's lost.
A special section just for steam engines and boilers, as without these you may as well fit a sail.