I recently was perusing an auction and found several interesting items, including this gem. It is a 1903 Springfield rear sight micrometer, similar to the PJ O'hare tool, used to set the rear sight more precisely.
This one was sold by the Westchester Trading Post. Apparently, back in the day, the Westchester Trading Post was a well known fixture in target shooting circles and their products were well thought of. The Westchester Trading Post sight micrometer was manufactured by L.S. Starret compnay, the well known precision measuring tool company.
https://pronematch.com/the-westchester-trading-post/
This one was sold by the Westchester Trading Post. Apparently, back in the day, the Westchester Trading Post was a well known fixture in target shooting circles and their products were well thought of. The Westchester Trading Post sight micrometer was manufactured by L.S. Starret compnay, the well known precision measuring tool company.
https://pronematch.com/the-westchester-trading-post/