Alliant shows some Fio 616 data, but not lots. This seems to be the mildest primer available, milder even than the Rem 209.
I bought quite a stock of Cheddite 209, and ended up selling most of them. They tend to punch through, especially in my Browning XS 20ga. One firing pin sort of eats up any 'savings'.
I'm back to WW209, which have never given any problems. The cost difference is indeded $0.0067/shell. After seeing a 3% rupture rate on the Cheddites, I figure I can afford the extra cost of a real primer.
