Just about everything the boys have said and then some. Synthetic BP and sidelocks do not work well together. Now as to 777 take that to the tenth power. 777 needs a hotter ignition to fire right. I learned that becauseI was very pig headed and had to try it myself. Big waist of money!!! If you can't find any, try some Goex Pinnacle or Pyrodex RS. They should work much better with the musket caps. And use Dave's method of tilting the rifle to the side and hitting it with the flat of your hand to get the powder in the bolster and get closer to the nipple area.

Now as to a good hunting sidelock I would replace the nipple with a musket nipple and also go the the darkside (Black Powder). Don't live in your area, but I am sure you will find some somewhere in your area. Do you have any N-SSA guys in your gun or hunt club? They have to use the stuff in their matches.

Now as to the best part, testing for a good hunting load. This is the best part. In my .50 I have an InvestArms and it likes the .490 ball and a .015 patch. That works well in my gun. But as with everything to do with shooting and guns, each is definitely an individual and you will have to find out what it likes.

The rest is up to you and oh yeah, make sure you have a lot of fun doing it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Good luck with that tag.