NSXER
My problem isn't with Rio primers. It's with people that make irresponsible statements without data to support it. Yes I shoot and have shot trap, skeet, and other clay target games since the late 50's. My ATA number is of no consequence. Would that somehow convey some magical amount of knowledge or expertise that a non-ATA member would have? I've also reloaded shotshells and metallic ammo since then as well. When someone says primer x is the same as primer Y, they need to have some data to support it. You made the statement that they are about as hot as the Winchester W209. What data did you use to support that? Have you actually compared the data at the link on the page you linked to with data from other sources and data with other primers, especially the Winchesters you referred to? I'd like to see your comparisons and conclusions. The link to the pdf with the Rio supplied data is above.
If you read what Rio has posted on their site about the performance of their primers with certain types of powders, etc, then take a look at what characteristics the powders they recommend have, it doesn't fit many of the common powders we use for reloading in this country (USA). Large straight tube hulls and single based powders are what they were designed for.
I don't like Rio hulls or ammo. That's not a secret. It has performed dismally for me and personal observances of numerous basewad migrations makes me avoid them, even from the factory. The factory reps lack of concern and response about the issue was less than impressing. I will use Rio primers under some circumstances, but have found that they can drive pressures up in many loads. That's the reason I recommend caution when substituting them for another primer in the loading data. Common sense is not always that common.