If I recall correctly all Bill's PPC guns did not have the integral rib set into the bbl until he came out with the Windmaster post Nationals in Des Moines. This could very well be a Davis comp. gun set up for maybe action matches. With the bobbed hammer and trigger stop don't think it was a bulls eye gun. The yoke lock underlug(no ball detent I can recall) and adjustable trigger stop were some of his keynote features. His original rib made for him(I believe)by Aristocrat Sight Co. was the front adjustable model for the three sight settings.B0-Mars were the mainstay till then. I remember(JPE correct me if wrong)his guns came out right at time or right after Nationals came to Pearl Mississippi, from Bloomington Indiana(attended but did not shoot unfortunately). I know for sure they were at first Nationals I shot in at Jackson and in high demand. Austin Behlert showed up with some neat innovations along with Jim Clark Sr.