Number one, swapping primers is a crapshoot. If you have reliable data for the Fiocchi, why are you asking this question? Clays is not a good choice for heavy 1 1/8 oz loads in Winchester or Remington hulls. Call Hodgdon and get their take on it. Clays is fine for 1oz loads or lighter 1 1/8oz. It hits the wall pretty quickly, pressure wise. I don't load target loads to over 10,000 PSI. If I want 1200 fps 1 1/8 oz loads, there are way more suitable powders available. Green Dot and American Select come to mind. I also don't care for the Fiocchi 616 primer. I've had some of the most inconsistant loads using them, especially in colder weather.