I've noticed that several users here have mentioned the application.
Often I've seen 10.0 grs Unique suggested as a favorite Trapdoor load with 405-410 grain cast. In fact, I tried it myself and was rewarded with decent groups, no apparent problems.
A vague recollection brings up Bulleye in the Trapdoor for very light loads. That one took me by surprise.
The loads referenced in these applications seem to mesh with low-end data given in http://www.gmdr.com/lever/lowveldata.htm.
Those data are for Marlin lever guns if I'm not mistaken.
So I find myself wondering if anyone has experimented (and tested) light loads in Trapdoors with other pistol and shotgun powders that GMDR tried in lever guns? Thinking here of the Hercules Dots, 700X, HS-6, W231, etc.
Before anyone has a major coronary, yes, I know a Marlin lever is not a Trapdoor.