rafsob
I can only tell you what I do and it seems to work..
I use an old Remington primer - do not think it is even available any longer - it is a Remington 209-4 - built for 410 shotguns. And the other primer I use is the Winchester triple seven primer - both of these are much cooler than a regular Winchester.
So if I could suggest find the coolest 209 you can and try that....
This information is stolen from Toby Bridges ML site.
Winchester 209ML ........................221 f.p.s.
Winchester 209 Triple Seven ML.....244 f.p.s.
Remington 209 Kleanbore ML ........318 f.p.s.
Std. Winchester No. 209A ..............336 f.p.s.
Std. Remington No. 209 .................341 f.p.s.
Cheddite No. 209 ...........................347 f.p.s.
Federal No. 209A ...........................381 f.p.s.
And for comparison, we also ran the Precision Rifle "Vari-Flame" through this test, using both Winchester "Small Pistol" and "Small Rifle" primers.
Winchester WSP "Small Pistol" .......116 f.p.s.
Winchester WSR "Small Rifle" ........143 f.p.s.