see jellyhead makes the maximum now for M2 20's. Just wondered if anyone has shot it with Heavyweight 7s by chance. I know you not suppose to shoot ported chokes with the wad but i also was led to believe you could with the 20 gauge wad being it is softer then the 12 version.
I did'nt have good results in my remington 11-87 20 gauge with the choke and federal hw 7 you referred to. I say get a choke with no ports in it for that shell. Cluck