I'm not very familiar with the TC patent breech design, but with some patent breeches I use a thin piece of wire and insert it into the flash hole from the nipple end. The flash hole channels often have 1/2 of a corkscrew or spiral shape to them, and I'll bend the wire a little at a time until they will fit all of the way in to the powder chamber in the breech. I don't know if TC's are as easy to access for cleaning with a wire as others are or not.
I do know that TC rifles used to have a tiny clean out screw that they stopped building into their later production rifles because they were too small to be very useful for cleaning and they often were allowed to rust shut by the owners. So TC eliminated them altogether.
This picture shows some different breechplug scrapers. I think that the one in the middle is made by TC, I'm not sure about the one on the right. Using a breech plug scraper of the right dimensions for the TC breechplug will help to scrap out more of the residue that can eventually block or partially impede the cap ignition, which flushing with soapy water alone may not remove. Try to determine the size of the powder chamber at the bottom of the barrel and scrap it out after each shooting session to eliminate some of the residue build up and which may be helpful.
Between using the wire, the breechplug scraper and the flushing by forceful plunging with water, you should be able to keep the flash hole open to help insure better ignition.
There's a couple of other tricks too, including using the fffg finer powder granulation to see if that helps, and to remove the spent cap before loading and ramming the next load to help the air & powder flow into a drum or patent breech better when rammed. Pyrodex and other subs are said to require a higher ignition temperature than real black powder which is more explosive and reliable. FFFg or Pyrodex P usually burns cleaner and produces less fouling.
Sometimes a new Hotshot or similar aftermarket replacement nipple helps too.
The TC #13 cleaning solution isn't all that effective if that's the one that you're using. Maybe you can try another like Hoppe's #9 PLUS BP Solvent & Patch Lube or Rusty Duck Black Off BP Solvent (at some Walmarts). There's plenty of other good ones too.
