FA guns tend to have tighter barrels and throats than most others do. My 475 runs 475 bullets, most other 475 guns, all custom, use .476 or .477 bullets.

Every revolver needs to measured and have loads tailored to that gun, if multiple guns end up working with the same loads then you got lucky.

You need to get your hands on a set of pin gauges and measure the throats, order the appropriate bullets that have been sized correctly, and your gun will shoot. I get MUCH better accuracy from cast in my FA over any jacketed bullet I have tried. Montana bullet works offers their bullets in a variety of sizes for just such needs.

Good luck...