Took the revolver out to the range and tried it out. Did the forcing cone work help? Hard to say. I only ran a dozen rounds through it but the groups were acceptable, considering who was doing the shooting. I didn't notice anything coming out the sides, the reaction/recoil seemed a bit smoother, and close inspection revealed no traces of copper jacket clinging to the entry of the barrel.
That last bit is important as I had chunks of copper plating stuck there the last time I cleaned it.