The way I disassemble my M52 is to depress the spring loaded pin and unscrew the bushing sufficiently until it will swing clear of the slide. The spring can then be removed.

The 3.3 gr of 231 sounds high for the M-52. It will vary based on your pistol but normally 2.7 or 2.8 gr of Bullseye and 3.0 gr of 231 are used with the M-52. You may need to adjust for your particular pistol.