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.
I can second the cold weather lack of performance. Perhaps I will try the 617, I hear it is a bit hotter. In nomral weather I have no issues and am using anywehere from 16.6 of Clays with 12WAASL wad for 1 oz to 17.5 or so with Windjammer (downrange orange) for 1 1/8. I have not loaded any of the 19 grain stuff as we only shoot 16's and doubles in winter.
Red Dot with the same drop works fine also. I've shot and reloaded about 3200 shell with the Fiocchi 616's. Bought them when the Winchesters were hard to find. Not one fail to fire or blooper. I bought a case of them so I have many more to reload and shoot, don't anticipate any issues.
I have talked with Hodgdon, and Alliant about the replacement of the Win 209 primer with Fio 616! They both have assured me that these primers will swap out without any change to my recipe. Dont understand why someone would print all of the recipe guides to show such high pressures with the Fio 616 if they are a true even swap. Still a little hesitant to load a recipe with the same grains I am currently loading with the Fio 616??? Just a little confused!