Found some old patterns
CZ full choke 40yds 1 5/8oz tss #9, 207 in the 10"
CZ imp mod " " '' '' '', 197 in the 10"
CZ Full choke 40yds 1.5 oz tss #9, 234 in the 10''
As a comparison the Trulock flush .581 at 40yds, 1 5/8oz tss #9 avg. of low 200's with some small holes in it.
so for a flush choke .581 is probably starting to be over choked.
I spring turkey hunt with an extended Trulock .571 in the left barrel and a Carlson ext. .575 in the right barrel. in the .571 a tss load of 1 7/16 oz #9 has a better 10" than the 1.5oz or 1 5/8oz load.
Patterns in the extended chokes are better than the flush chokes
For lead loads,----- CZ full choke 3" Fiochi Golden pheasant 1.25oz #6 is a solid 35yds head/neck load
CZ imp modified same load ^^ is a solid 30yd. " " "
at 15 yds the pattern in the CZ imp mod was about 20-22", full choke was 18-20" with the 3" Fio. golden pheasant.