Daryl Pelfrey... I understand your desire for a BP, or for that matter, a print of any kind. Before I built my first rifle over 20 years ago, I had the same desire to come as close as possible to the originals. I now also build more precise pieces of machinery, that do require blue prints. But in 18th century gun building, it was more of an art than a science when it came to building a gun. Sure, some things needed some precision, like making a good lock, or positioning of certain gun furniture. Other than that, the ancient builders had little consistency.
The maker I have probably studies the most is George Shroyer (Scherer, Schoyrer, Sherer) of York county, PA. I have at least 15-20 photos of his stock profiles, and none of them are exactly the same. All are different from one another, yet they show commonality. These makers were not trying to turn out carbon-copies, nor were they trying to turn out works of art for art's sake. They were trying, and succeeding, at turning out guns that the public would pay money for. That is all. Today, the modern mind seems to value one-of-a-kind pieces with an undeserved reverence. Back then, it was just the way things were. How they would have loved interchangeable parts back then... It would have been a hard thing for the colonial mind to grasp, lol.
It is great to have the opportunity to have an old original, and make a bench copy, but most prints won't bring you the exactness which that experience can. Keep in mind, the only purpose for the barrel pins is to hold the stock tight to the barrel. I use 1/16" pins myself, and they are barely noticeable. The advice here to get books and study the pictures I whole-heartedly endorse, since that is all I have at my disposal to study. The two RCA volumes are indispensable to me. Also, a couple good books on building these guns will give you a wealth of knowledge, but practice of course, will always be your best teacher. Locate you pins where they look right to you when you compare them to original picture. I can't tell you how many times I have been advised that ramrod pipes are all equidistant from one another on original guns... They are not.
Matt