I had a Poly choke put on one of my 3" 870's that , I had backbored to .740 and it works pretty good with steel shot .
It is very flexible as , when you're in the field you can rotate it to the constriction you think you are going to need on
in-coming birds . I have found , if you pattern your gun with the load you like and see what setting shoots best at
different distances , then mark that spot on the choke adjustment with finger nail polish , this will give you confidence
and allow you to see it in the low light of early morning , with a glance !Make sure you clean in between each gap of
the choke each time you use it , otherwise it won't work right .
Old guns are Best if , left alone !