Very few, made from scratch rifles exist, either from the 1700s or from today...Most custom rifle makers today at least buy the barrel and lock already made...This was also true back before the American Revolution...American longrifles made prior to 1780 or so almost always had locks and barrels imported from England, France and Germany...
I bought my first flintlock back in 1977 and from then until the early 80s I seldom used a modern centerfire rifle...I made a .54 flintlock back in 1988...The barrel was inlet into the stock and the ramrod hole was drilled...I did the rest with hand tools...It took me 2 years and about 200 hours to complete...
Currently I own one inline and 2 flintlocks, a .40 and a .54...Until this year, I had not loaded my inline in over 3 years...I'm 55 and my eyesight just isn't as good as it used to be...I've recently found out that I have a cateract in my shooting eye, so a scope is just about essential for the time being...
Here is a picture of "Daisy"...This is my version of a 1770 era rifle that could have been made in Piedmont North Carolina...What I wanted was a rifle that Daniel Boone could have carried into Kentucky in 1769 or could have been carried at the Battle of Guilford Courthouse on March of 1780...I call her Daisy because she has a Lancaster Daisy patchbox...Many of the gunsmiths that moved to North Carolina in the mid-1700s came from Pennsylvania and for several years their guns would look similiar to the guns they made in Pennsylvania...
And here I am demonstrating her to a group of Boy Scouts at an event last year...