I have found a great double action with double underlugs, with three bites believe it or not and a third hidden fastner. This action also has side clips and is a large French 12 gauge. Considering the strength of this action I have been thinking of building a double chambered for one of the these three cartridges, the 470 NE, .475 # 2 Ne or the 500 NE. Which one would you pick and why?