lagopus, I think the "NOT FOR BALL" is authentic as it is accompanied by the 12B and 13M markings, and the alignment and spacing are right. I don't think it was made at a later date with separate letter stamps. Therefore, I think the date range of 1875 to 1887 is probably correct. Which would mean as you say it wasn't made by Midland. Tanky's gun is so similar to mine it's hard to believe at least the receivers were not made by the same company. Mine is evidently a few years older than tanky's. I think his gun also has the "NOT FOR BALL" mark, which would mean nether gun is a Midland since they wouldn't have used that mark in 1889. Could you post some pictures of W&C Scott guns? Thanks.