If you are still interested, I would highly reccomend the Lee 405 HB over 55 grains FFG. The Lee bullet is almost an exact duplicate of the orginal M1873 bullet, and has proven highly accurate in my Trapdoors. Seat it directly on the powder with the Hollow base clean, and you willl enjoy the results.
Pedersoli indeed uses the H&R Tooling, but did change the latch installation design. Best results are to use a complete block assy, will usualy drop right in. In any case, H&R did make a run of these with the latch cam machined backwards, but most if not all those were corrected decades ago. But the story never dies . . .