Larry,
The earliest factory records we have are contained in the stock books and start at S/N 1501 made in 1874. The earliest stock books in this range only contain basic info such as S/N, maybe barrel steel, and stock dimensions. Many S/N's have no information at all that can be read 140 years later. Order Books start in 1877 at around S/N 8,000 and this is where you find out who the gun was sold to, the price paid, and any other special instructions that the person who placed the order specified.
At about S/N 1780, the format of the stock book changed to a horizontal format. Now you start to see additional information such as stock dimensions, weight, and patterning information. Remember, at this time, you have nothing to base the grade of gun on because there is no price and if your lucky, it may say "Dam" so you know it's a higher grade but what what grade exactly we don't know. At around S/N 1850, the records are more complete with barrel length, stock dimensions and weight but still the grade and barrel steel is many times missing or unreadable.
Around S/N 4000 we start to see the type of steel used more consistently such as Iron, Lam, PT, T-0, T-1, T-2, and Damascus so we start to see the grade of gun being manufactured but they are still considered Dollar Grade guns at this time.
Once we get to 1877 and S/N's in the 8k range and we can view the Order Books, we are in the "Quality" grade guns and can base the Quality or Grade based on price listed.
Now you know why I cringe when someone requests info on those low S/N guns
This subject would be a good project for a PP article but don't look at me to do it
