To screw in hanger bolts easily, make up a driver from a threaded rod connector and two setscrews. You can determine the length of the installed stud by how far you drive the setscrews into the rod connector.
Screw the hanger bolt into one end of the connector. Then use a socket and ratchet or electric drill on the other end to drive the bolt into its pilot hole. A touch of paraffin on the screw threads will make the job easier.
Alan Dorr, Chico, CA