SASS has changed the rules to include fixed and adjustable sites together.
(Not much if any advantage when targets are 7 yards or so)
You would have to shoot all 4 of your guns in black Powder
to be in Frontier Cartridge class. If you shoot a mix,
most likely Cowboy class depending on your age.
I myself shoot a mix, to keep it more fun and interesting.
I started out for 4 years with 2 cap-n-ball pistols,
now use 2 1873's in .45LC.
Some match's are BP some are smokeless (trail boss)
Same for my .44 mag rifle.
So far only factory for 12 gauge.
If you are new to shooting , and Cowboy,
start out simple so you are not confronted
with imformation overload in the beginning.
ie: learning BP loading and the rules of the SASS game at same time.
try
www.sassnet.com for all the rules and imfo