Another trick is to use different angles so that you can reach further. You can rotate your A-axis for the section of the cylinder you are having trouble probing to get that extra little bit of reach. For a big cylinder that lies beyond the CMM's reach, you could use A-45B0 for Y+ quadrant, A-45B90 for X- quadrant, A-45B180 for Y- quadrant, and A-45B-90 for X+ quadrant, then construct a cylinder from all the hits of each cylinder