You could just shoot the .432 bullets and be done with it. There are a number of cast bullet manufacturers that will cast bullets in your desired size. I have this problem myself with some of the earlier S&W revolvers, and have had good luck ordering from Montana Bullet Works. They offer an LBT, 250 gr LFN-PB in .432. Beartooth and others have similar offerings. Be sure you are getting a flat base bullet, as opposed to a Magma design (rounded edges) to minimize leading.
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