4th picture down, 2nd rifle from top. Is that flames on the pistol grip checkering? It looks like a K, but I've never seen checkering like that.
Far too early to be a 99K: special order buttplate (hrb or shotgun?), special order fancy wood and higher grade checkering. That checkering was used on the Leader Grade.
Mine isn't nearly as nice as Don's, but I do have closeups of the checkering handy.