45-100 bullets

[Fogman01]

I bought a 45-100 Sharps for black powder silhouette shooting and I wondered what shape and weight of bullet is favored? I know round nose and heavy is good. But what weight and shape would be be best as a starting point? i.e. postell, money, creedmoor? 500 gr, 550gr? I have been mostly shooting other calibers for fun or working up loads for buffalo hunting - now I am ready to get busy with the silhouette and mid-range shooting. I don't have molds yet - I want to use store-bought until I see what my rifle likes then start casting. I know the rifle weighs 10# 8 oz with a 34" round barrel, but I do not know the twist.
Thanks for any help.