I copied this from the American Single Shot Rifle Association site:
"Few years back, I picked up a couple of original rifles, a .40-70 Remington rolling block..with English proofs, and a No.2 Ballard in .25-25 Stevens. I had heard good things about a then new to me black powder called Swiss. And since I had sense enough by that time to only use black in these antiques, I tried it. 1st. time out with the Remington, and 1 1/2 Swiss I shot a 1" group at 100yds...it ain't supposed to be that easy..and I was hooked. The little .25-25 likes 3FG Swiss...3/8" groups at 50yds. with 100gr. Ideal 25720. I must confess..I did try a light smokeless load in this rifle..and the accuracy wasn't there..and neither was the deep boom all out of proportion to it's size..and that greyish white smoke screen blotting out the target for an instant..it just wasn't as fun!"

That accuracy should collect a turkey!