Either thin the entire .230 width spring to fit,,that'd make it the same width as the other (orig 20ga?) spring and fit the peg already installed in the plate.
..or simply widen the slot in the peg to accept the wider spring.
The peg and plate though case hardened are probably easily cut w/a file,,many are.
If the file skips off the hardened surface, just anneal the peg by heating it (peg) till it turns blue and let it cool. No need to turn it red or heat the entire plate with it.
Does the wider .230 spring seem to fit the lock works OK?,,no binding with the lock bridle in place due to it's greater width?
These guns were not fitted with the greatest of precision and the differences in the springs may just be from that or from different era of mfg.
Work around it, but don't over analyze it.
If the lock plate is warped, that too may be preventing the bend from properly seating into the slot in the peg as it puts it out of allaignment slightly.
Bent lockplates especially thin ones even if hard (case hardened) can be straightened with a lead or rawhide mallet on a hard, flat surface with a few careful taps.
Don't over do it, they actually bend quite easily.
