You need to read what pressures that gauge instruction sheet wants you to use, I haven't seen any leak down gauge that will work below 50 lbs of pressure, but there are a lot of things in this world I haven't seen yet also
A single gauge unit probably wants between 80 and 100 lbs., my two gauge aircraft legal calls for 80 lbs static before starting and the using the regulator to bring the first gauge (left hand side looking down at them) back to 80 lbs. with the valve opened reading the leakage so I would see 80 Lbs. on the left gauge and say between 78 Lbs. to 0 lbs. on the right gauge with a hole in the piston or a broken valve