sawfish,
I own 2 .500WE's, both of which are FA's. One, now a convertible, was originally a Field Grade .50AE, which was retro-fitted with one of the early WE cylinders. The second is an octagon barrel Premier Grade. To my knowledge, no one has yet offered a .500WE Encore barrel. T/C did once offer one in .50AE, as did Gary Reeder.