I have 20 ga serial #205060 man. in 45. It has a blued receiver that does appear to be original. It also has a 28 inch barrel with what I think is a trap rib. I have compared it to another gun and the rib is 2 to 3 time higher. I thought it might have been ordered for kid to learn to shoot trap? It is field grade. I also thought since it was the last year of prod before the change that they might have put some guns together with whatever configuration they could with the parts left? Has anyone senn anything similar