It's a welbey and scott service rifle (MKI) with acid etched writing. Only the first 500 or so of the 1500 made had acid etching and there are only three known to exist with all acid etching present. Mine has most of the writing present and could bring over $2000 at auction in the UK. I'm betting that it is the only one in the states.
Yes, there is a capsule of ammo for the 2mm pinfires is in the picture.