I had a lot of trouble with inconsistent ignition with my flintlock when I first got it. The drilled vent was a bit behind the center of the pan, and FITP were common. So I had a Chambers "White Lightning" liner installed, centered over the pan and even with its rim, and now I don't even think about FITP. .530 balls with 10oz bull denim, Lehigh Valley lube (also Mr. Flintlock). I'm going to the range tomorrow for more experimentation, which, darn it, I just have to keep doing. At least, that's what I tell my wife.
Good combination - 10 ounce denim, not .010". I measure 10 ounce denim as being .0225" with my calipers squeezed tightly.
I had some Oxyoke patches marked as .018"- but I measured those at .015". Go figure. Oxyoke patches are not good patches due to mislabeling and lousy lube. Their yellowish lube is not too bad, but isn't very good. Their OIL lube is must plain waste of time.
We mostly use a water based lube for trail walks and plinking. We use WWWF with a bit of neetsfoort oil added. Shake well, apply to pre-cut patches and have at it. WWWF is Winter Windshield Washer Fluid. The oil is simply Neestfoot Oil (not Neetsfoot Compound). I add about 2ounces per point. The oil seems to slow evapouration in the summer time. Only lube up enough patches for the day's shoot. Those not used, lay out to allow the lube to evapourate. They will work perfectly the next time, if re-lubed the same as before.
Jason, your combination was a good one as to ball diameter and patch 'advertised' thickness.
I think most ALL of your loading problems were with the lubrication. The load you were shooting is a squib (baby) load in a .50 rifle. Most guys here with .50's, shoot 80 to 90gr. 2F - not 3F - they use 2f because it shoots more accurately, is easier on the patch due to lower pressure generated and fouls not at all with their ball and patch combinations.
The guys here, use Bob's and others advise above on patch lube - wet is the key here - water based for target, then an oil or grease-type for hunting where few shots are fired.
None of us has to wipe at any time while shooting. My bag has a vent pick and it is used only IF the vent becomes plugged with a piece of fouling.
Wiping the bore will push $#@* down into the vent's inner cup and cause ignition problems. Good for you, on being able to pull the load at home.
If we have a flash in the pan (FITP), we prick the vent and re-prime and try it again. If again it flashes, we re-prick the vent, prime, tip the rifle a tich, and using the short starter knob, tap the top barrel flat with the starter's knob. This will allow some granules of powder to trickle through the vent. If it again FITP, it means you forgot powder. Pull the ball or trickle enough FFFFG through the vent, point it downrange and fire again, blowing the ball out the barrel- fffffftthup.
If you insist on using 3F- fine - I would probably top out around 85gr. for plinking. Your rifle will tell you, accuracy wise what is the best load to use. You cannot pre-determine what the gun will shoot, but with experience, you will have a @!*% good idea.
It should certainly shoot better with 60, possibly 65gr., then if not using a .020" or thicker patch in normal .010" rifling depth, you probably will start to burn patches. Pick up ALL of your spent patches the READ them to see what the load is doing. Keep using .020" or 10 ounce denim and the lubes noted and you will be able to increase the charge to where the rifle really cracks on discharge and shoots accurately at 50 and 100yards.
Note, about any load- even 50gr. 3F will make a single hole at 25 yards off a rest- but usually falls apart accuracy wise past that range, ie: 50 yards.
It takes more powder to shoot accurately at longer ranges than at 25 yards. Shooting at 25 yards will teach you nothing about accuracy,. but will grow familiarity with the rifle and it's loading needs.
Have fun!