Stumpkiller,
As far as I can tell choosing between 3F and 4F is not a performance issue, but a matter of personal preferrence. Is 2F less reliable in average locks then or is it okay unless the lock is of inferior quality and strength?
I would like to try 2F in my .58 caliber (when it comes) if that's feasible.
Personal preference to be sure, but less yours than your flintlock's.
:imo: FFg is less moisture & fouling sensitive in a pan than either FFFg or FFFFg in hunting situations. If you're firing every minute, it doesn't matter as much. But if you're firing two or three times a day for squirrels, or at the end of a day-long deer hunt, give me FFg and a large flint/frizzen.
I had a Dixie Tenessee .32 that used 5/8" flints and was a pretty enemic sparker. That rifle I used FFFFg for priming. When I used FFFg I would just as often get a "klack-Pow" as a "ka-Pow". For whatever reason, in that gun the larger kernels didn't work as well.
My Bess threw a shower of sparks with a 9/8 size flint that looked like a photo of a party sparkler. 10X the sparks of the 5/8 size Dixie. It was just a much better made & much stronger lock all around. I never had a misfire in a hunting situation with that piece that I can remember. Always used FFg. It also had a big 'ol 5/64" vent.
Like with most things flintlock, you have to find whet works with YOUR rifle. I had a T/C Hawken that never loved me (my first flinter), but I used cut flints and didn't have a site like this to beg for help. Even with FFFFg that one had a 75% reliable lock.
I'd recommend giving FFg a try in your .58 at the range. If you get reliable flashes you're set. Always nice to simplify your requirements.
My .54 has a Jim Chambers Early Germanic lock, which is larger than a Large Siler. I'm planning on feeding it just FFg and will be disappointed if it doesn't thrive on that.