Originally Posted by Argo44
1875, June: "Not for Ball" stamp promulgated.

1878, 23 Feb - W.C. Scott & Sons patent 761 - aka Triplex Action, coil spring back action hammerless lock; incorporates the Crystal Cocking Indicator.

Thus this fine Scott dates between 1878 and 1887 (though It could theoretically be post 1887; There are 1888 guns with "not for ball" proof marks.)

Yes, I once had a 12 bore hammergun with both 1887 and 1888 proof marks.