Another point about the Hawken and it's place in history.  They were never "the Mountain Man's choice.  The greatest use/appearance of the infamous half stock percussion rifle was in the 1840s and 1950s.  Long after the beaver were trapped out and rendezvous were a thing of the past.

Dave

I echo Wills statement, excellent work and nice Schofields, thanks for the look see ...

tEN wOLVES 

I use cut down 45-70 brass and Big Lube Bullets from Springfield Slim in my original 76'. 50 grains of FF and a 1/8" vegetable wad, my accuracy improved greatly when I went to the 50 grains and added the wad, my rifling is very shallow.
Tully

http://www.whyteleatherworks.com/BigLube.html
 

.........In the Lyman handbook the BHN for wheel weights is ~9. The BHN for 20-1 is ~10. This means that 20-1 is harder than wheel weights?.......

-Win 1876

 The wheel weight alloy that I have been making for the past 10-12 years has always checked around a BHN of 14.  This is almost hardball . a 20-1 alloy will obturate much better. This should improve accuracy and may help with the breech end fouling.    I have experienced hard fouling just ahead of the chamber using Swiss Black Powder.  I shoot 44WCF and 45-70Gov't in lever guns. The cure for both of the times this has occurred is using a "softer" (colder) primer. In the 44WCF (44-40) is was using Winchester Large Pistol primers as I had a lot of them. These primers are hotter than standard primers but cooler than magnum. Switching to CCI 300 primers , at the suggestion of John Kort, cured the fouling issue and increased accuracy.  You may want to try the same load with a softer bullet and different/softer primer.   If using a Magnum Rifle primer, try a standard rifle primer, if you are using a standard rifle primer then try a standard pistol primer.
 Figuring out a black powder load can be a little frustrating , but when you find it the reward is great.

What a great project! I wish I would have found this post several months back while I was putting a 76' together. Funny thing is, they are quite similar looking. It's in 45-60, I shot it in two matches this fall that had Tom Horn categories!
Tully