underside of barrel.

I got this from a friend, who is friends with the great great grandson of the original owner.

It was 45/60, but has been reamed out to 45/70.
On the top of the barrel, someone has stricken out the 6 with a 7.
But on the bottom of the barrel, it still says 45 60.

There is nothing written anywhere on the receiver.

I am trying to figure out when it was made, to find out if it is a legal antique.

"Model 86s were serial numbered from 1 up. Located near the end of the lower tang." from page 32 The History of Winchester Firearms 1866-1992 sixth ed.

Original 1885's were serial numbered on the lower tang. Many times over the years lower tangs were replaced for one reason or another and many times the replacements carried no serial numbers. Also, sometimes owners opted to change straight grip tangs to pistol grip by heating and bending. Many times the numbers were lost in the process.
Phil

Oh snap...I misread 86 vs 85...but yep TenX is sound. Single shots on lower tang too according to the book. page 28.

Mine is on the lower tang

Spot on 10x! Your SS, has had some kind of alterations done to it! Albeit not a collector piece, they make great shooters, and a lot of fun!