I have a Parker Hale 2 band Navy in .577 from the 1970's fantastic musket

For 25yrd comp's I use around 50 / 52 grn's of 777 this would equate to 45 grns of BP / Pyrodex with ball and patch

I have a BP / Pyrodex measure tube and I fill it to 45grns and then on the RCBS powder loader, lock it and fill all my plastic philes.

I never use mini bullets as they just seem to be inaccurate

I find this amount of 777 gives amazing groups in the 8 / 9 / 10 ring at 25yrds for a smothbore musket.

777 is also not as corrosive and easy to clean after use

Steve