RE: Pyrodex RS
Pyrodex RS is a very good quality, well established,reliable burning powder. It will often times produce excellent accuracy where other powder seem to fail. As Lee mentioned, it is probably the quickest in the corrosive department of all the powders, but as long as you clean the rifle soon after shooting there will be no problem.
While many claim there is a 15% difference in power between the loose Pyrodex RS and the Triple Se7en 2f, I usually find if I were getting good accuracy with 100 grains of Triple Se7en for example, then 110 grains of Pyrodex produce the same accuracy. Whether the same velocity is there, I can not say. Of course with that kind of charge, an additional 50 fps mean really nothing.
Pyrodex does fowl a barrel, and swabbing is often times necessary. You will normally find the fowling soft and easy to remove with a simple damp patch. Actually other then Goex, I really like the powder to shoot. I shot lots of it for years and always had great results with it.