Stock Book Help

[Pa SxS]

While doing a research letter on a 1881 hammer gun, the stock book entry showed some extra information that is usually not seen due to the way the stock books were copied at Remington. I'm trying to figure out exactly what it is.

Usually the far right of the stock book copy ends with the weight of the gun. In some stock book copies, to the right of the weight column, you can sometimes make out the patterning information. From seeing an original stock book, I know there is more information to the right of the patterning information and as I remember, it contains the type of shell used for the patterning.

While reviewing stock book #6, I can see a column that I've never seen before on our copies. The gauges are all 10's and 12's and the column contains numbers and fractions. The only 3 I've seen are 2 1/4, 2 3/8, and 2 1/2. Are these chamber length's, drams, or something else. Usually if the chamber length is noted in the stock books, it's on the left side of the page.

Any ideas what those numbers represent? Perhaps some of the guys that did the copying know the answer.