ImbadBob: That is a set of Wiseco rings that have been cut to work with top pinned setup. The Wiseco rings are thicker and there is no Mahle style ring set available for them. John cuts, notches those and other people do as well. It works just fine and thats not going to wear thru a hard pin. I do see your point if they were run on a mild steel ring pin, but there's the stock F1 / Mahle (ring over pin rather than ring under pin) rings available for those which have more surface area at the ring gap.
Also John usually moves the pin over to where they get better oil on the ring gap. I do have several sets that look like the above, I just checked and thats why I'm editing. Never seen even one piston of his move the pin up like that . I think RacerX above knows of a set though.
Looked like a plain Jane Wiseco to me too, but I was not going to say anything. The Merc/ Wizard have finer lines and the ring pack spacing is differently. The 280 style also has the rings sitting lower on the piston, allowing for more weld on top of the pin.
So, as Jay has mentioned, John's hard top pin method works just fine for cast pistons and it sounds like he sends a few forged sets once in a while.
IMO Johns method works just fine if you are reusing your used Mahle, 260, 280 side pin pistons . That was my whole point I was giving the guy as an option, and how this whole discussion got sidetracked. If you want NEW, then buy the Wizards. If you can't afford them and you have GOOD used pistons, send em to John.
If you are reringing a mild steel top pin model, please at least check to see if your ring is wearing into the pin.
If you have Marles top pinned pistons and are reringing, check to see if the pins are working their way up.
BTW, there are some very cool SOLID CARBON pistons being developed currently .
Expensive, but they sound very promising. Take a ton of heat, much lighter, super low friction, almost zero piston growth for tighter sealing, stronger as they heat rather than weaker like steel, etc. I believe someone in Europe is working on them. Formula One or something.