Powder pellets in Walker or dragoon
Get some real black powder and forget about these pellets. These substitutes are for the most part VERY corrosive and according to some people with good knowledge of chemistry,the fumes (smoke) from them can be harmful as well. Real black powder loaded into a long cylinder like these pre 1851 revolvers have is safe in the amounts you mentioned. My personal experience with this type of gun and muzzle loaders in general go back to 1951. Felt recoil will be about zero in either the Dragoon or the Walker. I had a new 3rd Model Dragoon and shot it a lot. It was one of the Colt marked models from the early 1970's.
Bob Roller