A few of us over the years shooting CLAS have found that velocities in the black-powder range are perfect, so between 1100-1500 fps with cast bullets. This allows you to use the heaviest bullet possible in any smaller calibre such as a .30. In .45 though all you need is a 300-350 grain bullet. Easy on the shoulder & cheap as you get many hundreds of shots from a tin of powder.
Slug your bore, just a pure lead slug very lightly tapped into the muzzle is enough to get a close idea of what your bore measures (find a sinker that almost fits these are pure lead). Make sure your cast bullets are several thou' larger. If you have micro-groove, don't worry, cast shoot just as well in them. Just make sure your bullet is oversize, you might need 4-5 thou' more, each rifle is a law unto itself.
Lube the bullets with something, (don't use them dry regardless of what folks say - those grooves around the bullet are meant to be filled with lube) there are hundreds of lube recipes plus commercially made stuff, try just beeswax & vaseline in a 50/50 mix, you can just lube your bullets with a finger when your starting out.
An almost perfect cast bullet powder for CLAS in 4227 (Australian made 2205). For .32-20 try 9-10gns, the 30-30 family of cartridges & .35 Rem start at 13gns, for bigger cases like the 45/70 start around 17gns. These will be very mild and easy to shoot.
To test accuracy put the rifle chicken at 200m & shoot offhand at it. If the bullet goes where you point it, load development is almost finished (this is also good training for trigger control & follow through). To check your ram load just set the rams up with the full foot on the rail and shoot them from 200m. If your load will roll the "hard set" rams then load development is finished.
If you get everything right, particularly the bullet size you shouldn't have too clean the barrel ever again with that sort of load, assuming that your lube is non-corrosive. If you have lead in the grooves it will be normally one of two things, an undersize bullet or to much speed. (The only barrel I clean these days are my BPCR guns as I don't shoot copper anymore.)
Anyway that's my humble experience for what it's worth with cast for CLAS matches
Good shooting
Mick
Oh I almost forgot. Regarding sight settings & getting mixed up in the rush before the detail starts. It's easy, set your sights for the next target as soon as you finish the targets you are on. This is when you normally have the most time, are thinking clearest & are the most calm. Then next time you come to the line you just check your sights & away you go.