First, ignore the machine cut flints. Yes TC sells them or used to and you can find them marketed by other companies. I've had folks tell me the TC lock for flints needs to have the cock replaced for better geometry for better sparking..., well with a knapped, English flint, never had a problem.
Second, get a few mail order flints for this hunting season, then next April, as you're in VA, better schlep up to the Fort Frederick Market Fair, even if you only go for a day. Then hand pick the flints for your lock from the half dozen or so folks that sell them. Plan on buying a couple dozen, so bring some good cash. They don't spoil, the price is only going to go up, and if you change rifles with the newest one taking a different size, you can always find somebody who will buy yours. I keep a mason jar full of the three sizes that I use.
LD