answered my own question, I think:
Regarding the 'Kentucky Long Rifle' used by many in the revolution,
How they adjusted for range, by adjusting the charge!
"When once the proper charge was determined the hunter made him a little charge cup to hold just the proper amount, usually from the tip of a deer's horn, and this was suspended by the bottom (to keep it dry) from the powder horn. "
....
"the sights were in forest country adjusted for one hundred yards for full charges and one hundred and fifty yards for double charges."
Thoughts on D. Boone's Gun
Link Removed
interesting read.