Some yr ago , let's call pre nontoxic shot , Win 209s were the lowest pressure standard primers following up the line to Rem 57 , and 2-3 other 209s . Strong caution was made about substitution of any primers in any load combination but especially the use of the Fed 209A where it was not the specific primer called out . I saw data , Ballistic Products Inc I think , that demonstrated in a 12 ga trap load a rise of 10kpsi from the W209 to 209A . That's a big deal when it jumps from 8600 to 18000+ . For whatever it's worth the Rem Nitro Mag steel cases are marked 1050 BAR right on the cases , I'll save the math that's 15,000 psi and that's a hot load load for anything 12 ga .
When you move into Mag primers the Win 209 M was only a little hotter than the 209A but again the further up you go the more the pressure can climb with any given load .
I don't know if it's good or bad but Federal changed their 209A dropping it down in pressure contribution to fit in with the rest of the standard 209s about 1992 and marked it as a 209 .
The 220s were most likely a mag primer .
Food for thought .
The pressure examples may have been in the Lyman 3rd edition shotshell manual , the one just before they added all of the steel shot data .