you wont get over 40 psi at that location due to the bypass valve relieves presssure. it might indicate 40 at start up with cold oil then drop as the oil warms.
if you watch the guage closely and know your engine you can see the pressure drop, with time as the oil filter gets dirty. after you replace the filter it will raise back up again.
with a new engine, or after any major engine disassembly. or after changing oil brands/types you need to change your oil filter right away.
the oil pressure guage is very informative in this area on this engine.