Well, in my experience, its hard enough to simply find a used Bisley in any caliber. Then, finding a 5.5" barrel is even more difficult as you usually only see them in 7.5" barrels. You can find all the BH's you want in various barrel lengths, but Bisley's are a whole different story. As far as .44 vs .45, either one will be fine. Personally, I think the Bisley is best served by the Colt, but they do equally well in a .44!