Over the years, I've built 12 rifle "kits" bought from Pecatonica River Long Rifle Supply.
Some of these were the standard kits they offer in their catalog and many of them were based on their parts but the parts were of my own choosing.
I've never had them breech a barrel but I have used their services to mill the sight grooves and install the barrel underlugs.
Their prices were always more than reasonable and the quality of their work was great.
On many of the rifles I built I wanted to use a different lock than the one they cut the lock mortise for so I called Dick and told him what I wanted. A XXXXX stock the barrel channel cut for a XXX octagon barrel (or whatever) without the lock mortise. He was happy to sell me exactly what I wanted.
All in all, Dick Greensides, the owner is a great guy to work with and he knows all about building muzzleloading rifles and is more than happy to help resolve any issue a buyer may have.
I believe his company sells some of the best curly maple for the money. That is, what some places would call a #4 grade, he sells as a #3 grade. (Higher numbers have more stripes and the stripes are more uniformly spaced.)
Most of the rifles I've built from his kits were bought with #3 grade CM and I was never disappointed with what he sent.
It is rumored that his company supplies most of the stocks Track of the Wolf sells and IMO, Pecatonica's prices are almost always better.
These are all #3 grade curly maple stocks.
They look a bit different because no two pieces of CM is the same.