I have a 539 that I scratch-made a barrel bushing for in attempts to improve accuracy. And it did!!

My barrel has a slight taper down the whole length, it was fairly easy to make a bushing that locks the muzzle perfectly when in battery.

I've been tossing around the idea of sending this pistol in for a single action conversion for quite some time, just haven't pulled the trigger!!

A parts list to convert it myself would be great!! I guess I should start looking at schematics and available parts.