Pistol Pacs have been specified by a “P” then the model variety of the revolver frame, then the barrel shroud form (blank) for normal, “V” for vent, “VH” for Vent HeavyExciting idea, I maye have to test it at some point. Just comparing The 2 guns facet by side, it appears like the .357 barrel from the Model fifteen is bigger on the surf