I have the Lyman 50th manual and have been planning to load some smokeless cast rounds for my 1886 win/miroku in 45-90. This is just to get started and I'll start playing around with BP soon.
Anyway, I am wondering if the cast and smokeless load data that is in the Lyman for this cartridge would require fillers in the case? Sure not... I think I read earlier in the book a statement about never doing that.
Anyway, I have a 405gr cast bullet that is very similar to the Lyman 457193 pattern. It might actually be the same. It's MBC's buffalo#1 bullet. I was planning to use some 4198 that I have. Even they don't have this bullet listed for the 45-90, they have a similar 400gr bullet and the data for that is very very similar to the 405gr bullet I speak of when looking at the 45-70 data. So, I figured it should also be very similar in this case. I measured out their starting charge today to see what case fill would look like and it's a pretty poor case fill with a large amount of space. I would expect poor velocity spreads with so much space, but it is of course a safe load without using a filler for the exact bullet, powder, etc listed, correct?