GPR for your fist flintlock.
If you are right-handed, I strongly suggest you acquire an L & R RPL (replacement) lock.
My experience with a left-hand GPR flintlock was unacceptable. Since there is no replacement lock for left-hand rifle, I regressed to cap lock -- that is, Lyman replaced the rifle at their expense.
The essence of the problem is that GPR flintlock is derived from the cap lock. Springs are coil rather than "V." And frizzen, aka hammer in flintlock-speak, is neither weatherproof nor rainproof. These shortcomings do not mean the flintlock will not function -- it will. What they mean is that you will need to be significantly more thorough, more diligent in maintaining flint, frizzen, touch hole, and lock geometry because the lock will not be forgiving.
***
Having said that, an acquaintance built his GPR flintlock rifle from Lyman kit. He used the RPL. Partly because he is a good craftsman, partly because, except for the lock, the GPR is a decent rifle, his flintlock was comparable with any $1000 limited production flintlock rifle.
***
One last thought. GPR rifle barrels have exceptionally sharp rifling. You will almost certainly obtain truly bad accuracy for perhaps 200 shots. When the edges are worn in, all becomes better.
