I have bought the boys (2) 870's in 20ga. One only had 1/2 box shot thru it and is a true 20ga. The other is also v.nice (some bluing wear) but well used..20ga on a 12ga reciever w/vent rib. Both Magnums, both full choke. I think I will use the one w/vent rib and let him throw some lead thru it. Bought both for $500.
