I use 15.0-16.0 gr of Alliant 2400 with a 170 gr Lyman 311291. That gets the velocity to around 1600 fps, which is where a micro groove barrel will shoot cast bullets decently.

It seems like I've heard the 100 gr Plinker isn't noted for accuracy and for about the same money you can use a cast bullet.

Reduced loads for many calibers are posted at this site and are usually intended for cowboy action shooting.
Lever Gun Performance Studies