It seems I'm a bit 'late to the party', here. so I will mostly be reiterating the excellent advice of others (particularly Matthaias' advice regarding proper drivers) with one exception; the trigger guard looks 'normal' for an MS ordered with the single trigger option. Also, my initial emotion would be to agree that an original, uncut, MS should not be 'scoped but if you really do want it done I'd go with claw mounts as available from New England Custom Gun (
https://www.newenglandcustomgun.com/products.php?cat=279 ).
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NECG 'German Claw Mount' for MS
You may wish to find and handle a 'scoped MS before committing to such alteration. Fire it with and without 'scope (claw mounts allow quick one handed removal with replacement to exact zero) and see how you like it. Major Bonkers is generally correct about the high placement of a claw mounted or side mounted 'scope. The appearance is a matter of taste, it is how they were done 'back in the day' (my cased, 1922 proofed, M1910 wears a contemporary claw mounted Gerard 'B'), not only to clear the bolt but so that one may use iron sights with 'scope attached. Joel Dorleac, who has expertly restored MS and other classic rifles / stutzen has mounted 'scopes low on MS per client specification, but the 'see through' function is lost in doing so. From anecdotes I've read, the 'continental shooter' of pre WW2 Europe was more accustomed to an upright shooting stance and was not bothered by high scope placement. It's a matter of preference.
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'Scope mounted low on (post WW2) MS in '458 by Dorleac
Regardless, 'scoping an MS is a very expensive proposition that should absolutely be performed only by an expert craftsman who has successfully 'scoped many Mannlicher Schoenauers.
Back to the rifle in question:
By the photographs she appears to be a fine, completely original, Mannlicher Schoenauer M1903 stutzen (full stocked carbine) with receiver manufactured between 1924 (when 'Made In Austria' was added to front receiver bridge) and 1926 (when 'Oesterr. Waffenfabr. Ges- Steyr' was changed to 'Steyr Werke AG'). They were available with several options, including single or double - set triggers, custom barrel length, even "Stock of specially selected pretty wood", which may have been a box ticked when this one was ordered.
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Commercially loaded cartridges for the 6.5X54 are generally available (Prvi Partisan) unlike the MS cartridges of 9X56 (M1905), 8X56 (M1908, or 9.5X57 (M1910) which are typically handloading propositions.
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The 6.5X54 MS, as well as the others of pre M1924, will feed flawlessly when loaded with cartridges built to
the precise dimensions of original DWM or Eley (Kynoch) specifications.
Cartridges function in the Schoenauer magazine as pin bearings in a race. The rotary spindle and walls of magazine housing are machined to the precise clearances of original cartridges and cartridges of shorter overall length or of different bullet profile may tend to jam, particularly if there's not enough 'meat' at the top third of the projectile.
Build them precisely like this and they'll feed like melted butter on glass:
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If you purchase the arm, here's how to determine when it was proofed.
Carefully disassemble
with properly fitting (thin) driver tips and find marks in this format:
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The image above shows an M1903 (C 6.5 denotes 'caliber'), Steyr serial number 4143, the 411th arm to be 'Nitro Proofed' at Vienna in 1908 (411.08, NPv)
Again, guided only by the images supplied, I'd say purchase it before it gets away. If its in your budget (or you can make it happen) and you miss it, it may haunt you for years.
The pre WW2 MS are highly prized by those who know of them and the 6.5X54 is, by far, the most popular of the original MS proprietary chamberings. It was the 6.5X54 that cemented the reputation of MS as light, handy, accurate, and supremely 'pointable', seeming to nearly aim themselves when brought quickly to the shoulder ('snap shooting'). Their smoothness of function and reliability is unsurpassed.
Here is a half ton of additional information regarding der Mannlicher Schoenauer (as if you're not already 'sold'):
https://www.africahunting.com/threads/mannlicher-schönauer-prewar-m1900-m1903-m1905-m1908-m1910-m1924-m1925-or-high-velocity.47277/