Fill an unsized case with powder up to about where you think the projectile touches.Add a card wad and push your projectile down onto the over powder wad.If you hear a crunch and the bullet sits naturally in the unsized case neck at the point where you seated it with your reduced loads,you now have your maximum charge.
Your not dealing with smokeless,your not going to grenade the gun.
I fire 110 grains of Swiss 1.5 FG behind a 780 grain Conical Ball from a tapping breachloader made in 1854 for a bit of perspective.
For the back sight,try peaning the pin at each end with a spring punch.
I have never used Card Wad with Backer Rod but if you want to then why not.I only ever use card over BP or A Felt wad/Grease Cookie/card wad stack but back then I was single
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