Model 1886 40-70 WCF question.|Winchester Rifles|Forum|Winchester Collector

I have a Model 1886 in 40-70 WCF that has been in my family since around 1964. We shot the gun from time to time, it is in good condition, we have cleaned it and kept it oiled up like all of our guns but not done any hunting with it because of the cost and availability of ammunition. I decided to do some research on it, just out of curiosity at first but also to make sure that I have it properly insured. 

This rifle has a 20-inch octagonal barrel, most everyone I have seen listed has a 26-inch barrel, does anyone here know if 20-inch was a factory option? I am working on figuring out if I can post pictures on here.