Pick a couple of powders that give the greatest velocity with the starting loads and start with those, that usually, but not always, works for me. In general the more accurate, consistent loads will be the ones that fill the case to 85% capacity with a starting load.
I've got the country for them I see them fairly regularly while I'm out riding colts or feeding/checking on cows or whatever. Surprisingly enough I've rode up on them curled up behind a mesquite bush out on a wide open flat, no trees/brush for a mile or more around. I'm thinking that its more...
If bobcats are the easiest to call in then I'm missing something. I've called in a bunch of coyotes and been busted or skunked by a whole bunch more but I never have called in a bobcat. Could be that I never saw them I suppose, I never thought of that.