I will say I never had a misfire with my flinters here is why:
I use a new flint tom fuller BEF and if I strike the flint it becomes a range flint:I set up my flint to be 1/16 away and make sure it will hit square on the frizzen.
I also use a bevel down set up
I always carry a use flint if I need to unload the charge in the field
I also polish my frizzen and lock were the powder charge sits. and wipe with alcohol the complete lock and frizzen:I also do not use any breech plug grease on the ventliner and my barrel first shot clean runs the same pattern as a fired barrel.