Hi, guys,
IIRC, the captive spring assembly on that pistol is nowhere near as complex as the one on the Radom, but it is not meant to be taken apart.
Again if I recall correctly, the spring is held captive by virtue of a washer and then the end of the guide rod is peened over. If this is the setup, replacing just the spring involves keeping the spring captive (I drill a hole through the rod, compress the spring, then insert a pin in the hole to retain it). With the spring held captive, you have to hammer down the peened end at the sides so the washer and spring will come off. Don't grind or file the metal off, you need it for reassembly. Then you replace the spring and washer, then re-peen the end of the rod to hold the whole business in place. Or you can just convert to a non-captive spring.
If I am correct, you can see why I didn't recommend swapping springs for the fun of it on that gun.
Jim