I normally ran Federal 9 BP 9mm standard pressure 115 gr in mine, but also Cor-Bon 115 gr +P as I recall. A more pointed bullet and/or a 124 gr or 147 gr might resolve things, but I'm skeptical. What was really needed in my opinion would have ben an extended tube magazine and different spring to resolve the overpressure on the feed lips, or a better engineered magazine. Apparently the issues were addressed and successfully surmounted with the P239, but the results apparently weren't transferrable to the P225/P6. P225/P6 and P239 magazines ARE NOT interchangeable.
Best, Jon