Used two 50 grain Pyrodex pellets interchangeably with 100 grains of loose RS in my rifles for years. Both worked very well for me and i like the convenience of the pellets.

You get fifty 100 grain equivalent shots from a pack of Pyrodex pellets. 100 measured grains of Pyrodex RS weighs right around 70 grains. There are seventy 100 grain equivalent shots in a pound of Pyrodex RS.

Going prices at the local Chairman Mao store:
One pound of Pyrodex RS = $19.95 x tax = 1.085 x $19.95 = $21.65.
Pack of 100 Pyrodex pellets = $24.95 x tax = 1.085 x $24.95 = S27.07.

Price of powder per shot using Pyrodex RS = $21.65 divide by 70 = $0.31.

Price of powder per shot using pellets = $27.07 divide by 50 = $0.54.