For those of you considering a kit, here is the reality of what is available.
I hope you understand these "kits" offered by Track of the Wolf, Pecatonica River, Jim Chambers,Muzzleloader Builders Supply, etc are far from a easily built "kit". In fact, they could be more properly called a "box of rough parts kit".
Absolutely nothing will fit.
The only things that come close to being finished parts are the lock and the trigger. Even these parts require locating, drilling and threading the holes for the screws that hold the parts to the stock. The barrel will need to be draw filed smooth before it is browned or blued with the exception of a Rice barrel that is mostly finished.
The barrel is not finished. It is rifled but the sight dovetails are not cut and on many of them the breechplug is not installed. This applies to the trigger guard, butt plate, side plate too. These are just rough, unfinished sand or lost wax castings.
All of the parts will need to be inletted into the wooden stock. This applies to the barrel, lock, trigger guard, butt plate, side plate and ramrod thimbles.
Speaking of the stock, even it is just a moderately close roughed out blank which will require a LOT of wood removal to be close to the real longrifles. A precarved and inletted stock can be a good thing if all the shaping was done carefully and precisely, which is seldom the case.
Knowledge of metal and wood work is a definite requirement.
Plan on spending a minimum of 120 hours of your time to finish your gun. Actually, for a first build, a number like 180 hours would be closer if you want your gun to be something you can be proud of.
I'm not telling you all of this to discourage you. I just don't want to see anyone go into this with the idea that the gun will be ready for assembly.
Speaking of ready for assembly, Traditions, Lyman and Pedersoli offer kits that are easy to assemble and finish.
These are basically the same guns these companies sell but the parts don't have their finish sanding and finishing done.
These "Big Factory Kits" are indeed, true "kits" with all of the threaded holes located and finished.
They require something like 15-30 hours of your time to finish depending on whether you wish to make modifications like reshaping the stock or installing inlays or wire inlays.
If you want an actual historically accurate rifle or fowler the so called parts kits are the way to go but are pretty involved.
My first two gun builds were not from kits but from a block of wood and a pile of parts, this is called a scratch build.