Rob- I know how you feel about sharp points on hooked butt plates. That one, especially, but being a mild kicking .40, not as bad as a .54 or .58.
Hooked in the arm/shoulder joint might work, rather than the bicep, unless the stock length allows that out on the arm hold.
About those patches. since you've fired approximately 200shots through it, the feather or sharp edge of the rifling will be long gone, from shooting and cleaning.
I suggest the crown might need some modicum of "work" to smooth the machine-cut corners. This will allow using a thicker patch that will eliminate burning and cutting
in one fell swoop.
The end of your thumb, twisted in the muzzle with wet/dry paper or emery cloth in 320 grit, will smooth the edges. What this does it allow the ball and patch to
form/conform into the bore at the muzzle. Once inside, they are easily pushed down the bore. Small calibres like the .45 and smaller, are easiest loading with tight combinations.
The smaller the bore, the easier.
A wet patch helps immensely - wet, not damp or dry and having to wipe of losing accuracy is gone. You will be able to shoot all day without having to wipe the bore.
The bore will get wiped as you load the next patched ball.
best wishes
That is a beautiful rifle, btw.
Daryl