You can use any of the Ruger bolts as well as the Volquartsen bolt. I have always used the Ruger 22/45 mainspring housing
or the Volquartsen housing which I have found no advantage over either. I own 3 of the Volquartsen 1911 style Target Frames
that I swap 6 different uppers on. My favorite is this PacLite upper that has been shortened to 3 1/2". I have the barrel lugs no the
frames adjusted to different positions so I can swap uppers by using hand pressure.