Andrew,
The cylinder looks like a Ryobi, but I haven't seen one with dual transfer passages before. The reason for the wide bridge in the middle of the transfer area is to provide a support for the trust side of the piston. Now it appears that there is no support and it will wear very fast. Ryobi's have a tendency to wear in this area with a stock cylinder. If the drag isn't to great, it will produce more power. Are the two pictures on the right from a Ryobi?

Dave