Post number 1 for me here.
The very first thing you need to do with a TC flinter is see that it is empty. Use the ram rod as the guide. Run it down the bore and dig your thumb nail into it. Remove it, and align it next to the barrel. That marking you made should be at the muzzel, and show it has run to the point and perhaps past the vent.
If not the gun is either loaded or has crudlings living in the bore. If so investigate... If not move to
Step 2. Install a good sharp flint, in either thin lead or a piece of leather you make to assist holding that rock. If you go with leather, it is a good idea to use soft and suple leather, and slice a hole in it to pass the hammer less the screw and the top jaw, so then you can never loose the leather pads.
Step 3 make sure it sparks, as a great deal of TC guns don't spark well. If not get caseinite and someone who knows a little bit of heat treating. You simply must have a good spark.
Step 4 get who ever case hardened the lock to stick around, and with more heat set the cock to toss the sparks in the pan and not throw all of them to far forwards. You heat and bend the cock to do so, more or less bending it down.
Other wise do as most of these guys say, but ALWAYS use a powder measure, which you can make to toss a measured amount of powder with. Never load directly from the horn.
I would use black powder all the time. You can play with other's but bp works better than anything else.
You could have a .45 cal in which case FFFg is a better load to no more than 80 grains. You might have a .50 bore and then FFg is better suited and to no more than 110 grains.
Most of the time a far less charge is more accurate, and begins at apx 45 grains for a .45 and 50 grains for a .50.
All my flinters go off upside down, and there is no discernible difference from a cap lock.
Cleaning is easy. Pull the ram rod, pull the wedge, cock to half cock and pull the barrel. Use hot water and add a soap if you like. Brush it, mop it dry add what ever is your favorite oil.
Something I do and others do is make a gasket from a brown paper bag to place at the breech and as far forwards as the lock goes.. This is oiled with pure linseed oil and trimed to fit with the barrel in place, and that gasket stays in the stock. It helps prevent powder from getting in the lock mortice.
