It was very likely a factory Mauser 30-06 sporting rifle these were marked u.s 1906 and aren't to uncommon, They were very poorly received and I think Edward Crossman wrote the article really trashing them for most importantly the bore dimensions being fairly out of wack. I would say because of this he owner sent it out to Sedgley to fit a new barrel, this is a service they offered and there are many examples of rifles just fitted with a sedgley barrel. Pretty cool gun, The sight is an Armstrong also a later addition. Sedgley did catalog a magnum Mauser but I don't think this has any thing to do with that.
