Interesting muzzle/sight cover for 1903?

[MPF]

I picked up a nice unmolested early 1903 today that had the pictured sight cover. I'll post some pic's of the gun later but it is 868xxx serial number with a 1-18 barrel.

At first I assumed it was a post war commercial piece. However faintly scratched into the side is "Cathcart 53 Regt" Unfortunately it doesn't show in the pictures.

Any 1903 aficionado care to tell enlighten me as to whether this was Gov't supplied or a piece of personal equipment. Also how rare are these? I don't remember ever coming across one at a gun show. Value?

[reincarnated]

Just a guess, but this looks like something marketed at the National Matches, much like the P. O'hare sight micrometer, etc.