My understanding was that they were simply a higher grade sporting Mauser purchased by the more well-to-do Boers shortly before they all went "Commando". Having greater means, these "gentlemen" preferred not to settle with a more pedestrian stock military class Mauser. There aren't that many that survived in top notch original condition. If it hasn't been messed with and is indeed in original question, I'm certain it would be worth a premium to any Mauser collector. BTW, there was a recent article in Rifle Shooter Magazine (I think) on the very rifle you're describing.