I patterned my Mossberg 20 ga. (with a polished barrel) with both a pure gold .555 and an undertaker XTHD .582 with federal HW #7, hevi #7 and hevi #6. My barrel has been polished as well. The following are my results in a 10" circle at 40 yards. Just thought I would pass this info along in case it could help anyone else in their choke/load combo and approximately what to expect.
Pure Gold .555
HW #7 86
Hevi #7 122
Hevi #6 81
Undertaker XTHD .582
HW #7 104
Hevi #7 127
Hevi #6 100
I think all 3 of these shells give me a legitimate 40 yard turkey killer. I was really hooping that I could get a little better numbers form the HW #7's. The gun is primarily set up for my 11 year old son to use so I do not need it to be super tight but I was hoping for HW numbers in the 120-130's. I see where others have gotten significantly better numbers than this. Should I try a .575 non-ported undertaker, a tightwad, or just leave well enough alone and quit wasting money shooting paper and go kill some birds?