Which granulation for my first loads?

[Flintlock Hokie]

My Shiloh Sharps in .45-70 will arrive in about a month. I'm almost ready to start loading shells. I always have 3F on hand for use in my flintlock and I'd like to use it in my Sharps. It should be cleaner. That's good. What am I missing here? Would I be making a mistake trying to use 3F? If so, what granulation should I start with?

I use Swiss in my flintlock so I'll probably use Swiss in my Sharps.

Thanks!

[Don McDowell]

1.5 and 2f are the most popular Swiss powders in the 45-70.

[rfd]

i also only use swiss 3f exclusively for all my flintlock long guns, too. when i decided to go exclusively black powder for my 45-70's and 40-65's, i eschewed testing, followed conventional wisdom and just went directly with what most of the top shooters use, swiss 1-1/2f. i'm very happy with that powder brand and granularity, and it burns quite "clean" with easy fouling control.