Here is Springfield 03 with a neat looking peep sight. (Not mine).

http://www.auctionarms.com/search/displayitem.cfm?itemn...with%2003a3%20action


Looks like an original bolt shroud with a lot of machining done to integrate a Rigby style peep sight.

That sight was made by George Hyde in Brooklyn, NY. The cheekpiece shape reveals the stockwork was by S.A. Leonard. Hyde was a superlative metalsmith who did a lot of work for Griffin & Howe. Leonard had been a stockmaker for Purdey and came to the US in the late 1920s or early 1930s. They formed a partnership. I think Hyde designed submachine guns and may have been the original designer of the M3 "grease gun" of WWII. Mike Petrov would know more.