It’s not the pentagon shape, it’s the different angle of the ratchet tooth relative to the hand; the five-shot starts “flatter”, requiring more force to move the cylinder.I bought mine with a 6.5 inch barrel used and it was ill fit up from the factory needing some ratchet filing to function on all chambers.
I fit a second cylinder to it and that also needed some ratchet filing along with some nipple well reduction clearance on two of the cylinders. I think the geometry of five chambers on a ratchet star works less smoothly than does a six chamber gun. Apparently a pentagon shape in rotation is not as easily made operationally smooth as a hexagon in rotation.
Did I explain that well?