I have an original '84 Trapdoor and back in the day, before I was lured to the darkside, I reload 38 grs. of IMR 3031 under a 405 RNFP bullet. Double check the Lyman loading book #47 for this info. They do not cover the 405 gr. bullet, but you can figure it our with what they list. I don't like the load listing at the Hodgdon website for this caliber. I think it is way too high for these guns! With the loads they list for the Trapdoor Springfield I use in my new 1886 Winchester (48grs).
These are my thoughts and you should work up loads, in careful increments, to suit your gun. Whatever you do, please research your load data
But all this is mute, if you come to your senses and load with the holy black. And have more fun I might add.