LOTS... first of all, it is clearly not a replica of any known gun. I started my planning by using mostly drawings in books, not photo of actual guns (THIS LED TO LOCK PROBLEMS :cursing: ).
Next, in making the stock, I used a CVA kentucky rifle for the general shape...so, the drop in the stock and the shape is not "historically correct", as opposed to a paddle butt or fish tail stock. Also, I used my caplock and flint rifles as comparison when inletting the barrel. When trying to fit the lock, I realized that the barrel and pan should be sitting WAY farther back on the stock.
Now, the lock...ahhhhh...the lock. :cursing: :cursing: :cursing: I struggled with it for a huge period of time, as I had used drawings in books and not actual photos of existing locks. The mechanics of the thing were not right, and it would either bind up or the dog would not "return" without pushing forward on the trigger/ sear bar. Actually, I had originally planned to have a sear bar and no trigger guard, but I could not get it right, and what you see in the photos works.
Also, the brass T/C thimbles, bore diameter, sights, etc, are not correct to any degree, but being "thrifty", it all worked in a pinch. Also, who ever heard of an oak stock?
Now, the following is my opinion only, and I only say this not to further any disagreement but to explain what I can live with: The next matchlock I build will look more authentic. However, I can live with a "functional" lock that contains parts that may be too "blocky" or that use screws, bolts and springs that are not truly authentic. Like all of my cannon projects, I try to make a "representation" of the original using the bench tools and skills that I have. To me, the fun is in the building and shooting.
PS: I thank you for your "genteel-worded" question, and I am not offended by what you are asking. I have great memories of building and shooting my first BP kit at age 14, a CVA Kentucky rifle. Although there are guys out there who would never own one for many reasons, it is accurate, fun to shoot, and will also introduce my boys to the fun of muzzleloading.