Hi,
I just fixed one for a client. I suspect they first came out with a percussion gun and then created a flintlock by fitting a separate pan (like a Siler), frizzen, frizzen spring, and flintcock. The external parts appear to be L&R early classic flintlock parts fitted to their percussion lock plate. The frizzen screw was drilled much too high through the bolster and lock plate such that there was only a paper thin thickness of metal above the screw. In addition, the screw was too short so that the head (it inserts from the inside of the lock) was only supported by the thin lock plate and not the thicker bolster. As a result, the hole in the lock plate broke under pressure from the frizzen on the screw. I fixed it by simply making a longer screw that also goes into the bolster for support. It was incredibly stupid for the manufacturer to use the short screw when such an easy remedy (longer screw) was available. The tang on the hook breech is straight with no bend. Moreover, they did not blend the stock into the barrel and breech, just left it high and straight so the top of the standing breech is set down below the surface of the wood. This gives the stock a clunky, hump-like appearance behind the barrel. The rest of the gun seems pretty good. The set triggers must be set to allow the lock to be brought to full cock. If you step back about 10-15 feet and squint your eyes, the gun almost looks like a plains rifle. It shoots pretty well, at least after I fixed the botched frizzen screw.
dave