I never reloaded for the 20, and can't comment on that, but, my 20s all made me seek out good patterning loads, more than the other gauges about the homestead. I had a bitch of a time finding 7/8ths oz factory loads that would pattern well in the last 20 SXS I owned. 1 oz loads were easy, but, thats what I have a 16 for.
Best,
Ted