Ran across an old 2013 thread
where a person did use a 125 WC in his M52 pistol.
However, he did have to us a spring that was 2 pounds lighter
for his slide to work properly with the fps and energy, of his loads.
If you go this rout, make sure to put the "Factory spring" back into the pistol
before you use the standard 148 gr loads
to prevent damage to your pistol !!
This is third hand advise, so use at your own risk.
His load with the lighter 125 WC was;
Bullseye at 2.6 grs that gave him 775fps in his pistol.