my experience ( which has been a lot with Rem 12 and 20)
For the Rem 12ga - shoot HEVI 13, #7, 3.5in. JH .660 or .665, HEVI .662 or IC .665 choke - you should be getting 250+ ( I think I got 280 on my best)
For the 20GA - Fed HW, #7, 3in, 1.5oz - IC or Sumtoy hands down. I have got 170+
For me... HEVI seems to work best in the 12ga,,, Fed in the 20ga.