Now I know this has been brought up before but I did a search and nothing came up. A couple years back I bought the anniversary 870 trap and for myself I found it had a very high POI. Now I have a opportunity to pick up one of the single shot "Competition" single shot models made in the early 80's. So my question is "What is the diffrence of all these models, TB, TC,Competition and the Anniversary. I know the Competition has the vent system but I'm wondering about POI.