I have been working on a few loads for my 3in 12Bore rifle , I had a ball mould made at .737 throws balls in WW at 587Gr , but I can still tap them down the bore with only the rifling makes on then !
any way I have loaded them with plastic wad down ,petals off & wad cup on that then ball & roll crimp ,this is the frist time I got a load that read each time I shot it though the chrony !
with other wads & fillers I got a different velocity with each shot .
I got Long Shot loads up to 2200+Fps , with some hang fires & dirty barrels & so so accuracy & moved on to AP 90 & shot this group at 50 yds 1923,1981,1934,1937Fps,but a little sticky on opening !

I'm shooting her from the bench & with the steel butt plate she drives it into me a bit , she shoots 1.5 to 2in a part I might need a bigger Ball ?