I bought one during the early days involving the "recall". Mine did not go back, as I fixed it up the way I wanted it. Still working on using the current factory parts to reduce trigger pull weight to a safe 3½ pounds. Getting close:
I ordered two of the 5½ Bull Barrel blued uppers from Volquartsen for $25.00 each. Both went onto the above lower as though they were made for it:
Ruger is now shipping Mark IV pistols with 10 inch barrels in blued steel, stainless steel heavy taper and the Hunter style barrels with sights. Yes, all Mark IV pistols are drilled and tapped.