Oquirrh. take a look at the following: If you happen to have fffg 777 it's a little hotter yet. youor 20gr of777 is safe enough, but I would be aware of the fillers unless using BP. I never use fillers fur anythin' just the lube pills. I set the ball down on what ever charge I load and shoot it. Anyway wanted to tell ya bout this here page. Here's the link.
http://www.hodgdon.com/loading.html
Use data specifically developed for Triple Seven FFG only.
All charges of Triple Seven or Pyrodex should be measured by VOLUME not weight. A simple, adjustable blackpowder measure is the correct tool for this job. All loads listed in this brochure are measured by VOLUME.
Triple Seven is a high energy product designed to provide the muzzleloading hunter with higher velocities when used in the same VOLUME as blackpowder. To duplicate a blackpowder load velocity using Triple Seven, you must decrease the powder charge by 15%. *See WARNING below.
Pyrodex is lighter in weight than blackpowder and weighs only about 70% as much as blackpowder. However, because Pyrodex yields more energy per pound than does blackpowder, the same volume of Pyrodex gives similar performance to blackpowder. Pyrodex loads given in this manual for muzzleloading guns are measured by volume, not weight.
Triple Seven In Cartridges: Use data specifically developed for Triple Seven FFG only. Cartridge loads should be used exactly as listed in this pamphlet. You may safely use a card or polyethylene wad up to .030" in thickness to protect the base of the bullet. Loading density should be 100% with light compression not to exceed .100". Testing has shown that Triple Seven will perform best when the bullet just touches the powder. Allow no airspace between the base of the bullet and the powder.
Do not reduce loads by means of filler wads or inert filler material such as Grits, Dacron or Grex.
Do not heavily compress powder charges. The use of filler wads, inert fillers or heavy compression may cause a dangerous situation, which could cause injury and/or death to the shooter, bystanders or damage property. Do not create loads for cartridges not listed. Contact Hodgdon Powder Company for recommendations concerning other loads. *See WARNINGS below.
I recemend you conider the cylinders chambers as cartridges.
Sheared the frame pins off my Pietta 1860 using this stuff with a normal load 28gr FFg777.
SG