I'm not a FFL but the FFL I use charges a flat $25 no matter how many firearms go through at one time... up to however many will fit on one form. I think it's ten??
my main thing was Capitol was already in the sellers system so I would not have to have a FFL send him the info. The FFL I used local is closed for upgrading his shop for the next 2ish months.
Plus I have not been to Capitol and wanted to check it out lol. And that would have given me reason to drive into Austin.