I bought a model 12 in 16 gauge awhile back and just started recently playing with it. What I noticed is the mag tube has allot of play in it. When I put the barrel and mag in reassemble everything I can spin magizine tube. Tube really only spins left if I go right take down pin hits barrel. Just seems that it's not tighting at all. It all stays connected when working slide but has to be something I'm missing to make sure it doesn't move and properly tightens, plus pin against barrel will mess bluing up. I took few pics to try and show.