Doc, google "Larry Gibson" there is a forum thread on td loads and techniques you may be interested in reading.
I found I can stuff another 3 grains of t7 into my case without exceeding the powder compression using a drop tube. 45.4gr fills my case so that the bullet sits at the bottom of the top grease groove. The grease groove is .100 wide so the bullet is seated to the bottom of the top driving band. I am using my sizer die to taper crimp the round so the top of the case is at .482.
Variations on this theme are limited to trying: softer lead of the 20:1 flavor; magnum rifle primers and a custom bullet mould sized to my bore diameter.
The last time I tried to get along with Mr. T7, I used a 405gr flat base bullet and a .060 fiber wad, 42gr T7, large rifle primer and drop tube. Not sure of the bullet alloy as they were purchased. Long story short, 1 out of every 4 or 6 rounds squibbed. Not happy. That was in '09.
Someone at the match suggested the TD book by Spence Wolf. The world suddenly changed!
Concurrently, I am working on BP loads and getting good results. Ultimately, I need to get the m1887 bullet mould and cast the 500gr bullet and just go with the one round. Nothing that time and money will not resolve.
For the upcoming shoot I am resolved to use the T7/405 combo for the first half of the course, and BP/500gr combo for the second half. That my friends is compromise...