i do not wish to step on toes but i have a couple of corrections since there may still be some people alive who knew him....
1 W.R. Hout was my father although Holt is a common misspelling,
2 dont know if hacker or dad made the powder horn but i do know it has FF in it.i normally shoot with FFF so i can be lazy with priming but i figured a day at the range with the hacker deserved proper procedure.
3 .475 ball with .010 patch but it doesnt make a whole lot of difference.i do want to try .015 patch
i assume the errors were made due to the pure excitement of the moment and after all there is no point in having it if you are not going to shoot it. that is what it was made for.
do you have a pic of the left side of the stock near the muzzle?