I have a Cody Ballard No. 1 in 40-50 Sharps Straight that I've been working with for a couple years now.  I had been using 3F Goex and 3F Swiss, but lately tried 1.5F Swiss on the advice of someone on the board here, and got my best results yet, (100 yards) 10 shots into 1.1"Vertical, 1.55" Horizontal, with 8 of the ten falling into .85" Vertical, .55" Horizontal.  3 fouling shots prior to the 10 shot group, blow-tubing in between shots.  Was using a 6X MVA scope.  It's almost breech-seated in that I only seated the bullets about .3" into the case, with two bands exposed, and only the bottom two grease grooves (the ones still inside the case) filled with SPG lube.  So the bullet is seated well into the rifling when you put it in the chamber.  Used 48.1 grains of 1.5F Swiss, and a Brooks "Turkey Killer" 420 grain bullet, 1/20 alloy.  average muzzle velocity was 1121 fps.

That was my first attempt at 1.5F Swiss in this cartridge, so I need to load up a bunch more and see if I was just lucky.
Vic