I am not familiar with Frontier bullets, so I can't comment, but the Campro bullets site suggests starting at the top of the cast bullet data, and work up from there if wanted.
The cast bullet load I use for .38 special is 3.0 gr of Win 231, and that powder charge was not sufficient. I got the odd one stuck in the barrel, which was not particularly dangerous because I was firing slowly, off a bag doing load testing. Now speed shooting would have been another matter entirely.
I quit shooting after getting a few squibs, and pulled the bullets out of the rest, so I could weigh the charges, just to find out what happened.
They ranged from 2.8 grains to 3.2 grains. My powder measure is the RCBS uniflow with the small cylinder. Maybe other measures are more consistent than that, I don't know, but to be on the safe side, I would say do not load to the minimum cast bullet data.