New shooter and new rifle, the perfect combo for miss fires.
New Rifle...
Any new flintlock I've had,even customs with the best parts, was finicky when new. As the gun was used it became better and better. For example my 28bore smooth rifle had to be picked regularly to fire when it was new. Now it only miss fires if the flint is dull or there is some obvious obstruction.
It will even fire now if the pan is goey from wet fouling. Sometimes it has to fire a string of shots that way as I am in Andrew Jackson's Militia of 1813-14. The first chance I get I wipe the bottom of the flint and pan out when conditions are like that.
Why it improved, I do not know, maybe it just needed to be shot. May be I improved along with it.
My rifle ...
It's a 45 caliber longrifle. This would classify as a custom build but it was not custom built for me. I had to do a little work to this one.
It needed the vent enlarged slightly and the pan deepened some. The frizzen was rough so it was polished,so was the pan. After this it loved 2ffg prime and main charge. It hated 4fg and 3 fffg as prime.
Now it will fire with 3fg or 2fg.
Why it has improved, I guess it needed to be shot.
I only swab when it needs it, like becoming difficult to load, not so difficult that I stick a ball!
My guns and rifles have benefited from having the frizzen and the pan polished.
You are not going to remove the "chatter" marks from a frizzen but it does help to smooth them. IMHO polishing a frizzen lengthens flint life and gives you better spark.
Polishing the pan and the bottom of the frizzen that covers the pan helps a lot IMHO. For one most locks have a textured surface that holds moisture and fouling. Polishing removes this textured finish reducing the tendency to hold moisture or fouling. Secondly when fouling does collect it is easy to wipe away, a small cloth will get nearly all of it, your finger or thumb can wipe enough of the fouling out for a quick following shot.
As a new flintlock shooter you need to understand that a flintlock burns powder. A percussion detonates it so to speak.
When loading a flintlock, You firmly set the ball on top of the powder, still allowing air to be between the grains. In percussion some will tamp, pack and really compress the load to get good results. This has the opposite result on a flintlock. The ball should be placed firmly enough on the charge to make sure you are not on a "crud ring" but not so firm to compress or pack the air from between the grains. This takes some feel, that you will only gain through shooting.
Use a damp not wet patch for swabbing. Never use a dry one if the bore is dirty!
I do not know why but even if you get flashes and still no main discharge, the flint can still be culprit, maybe it has to do where that weak spark lands. So even if you get a lot of flashes it still may be time to change or knap the flint.
Before you do any "work" like enlarging the vent and such shoot some more and report back with the results.
Lastly never shoot any substitute in a flintlock. They work poorly if at all.