The 6.5X54 MS (sometimes denoted as 6.5X53) was a proprietary cartridge developed for the Mannlicher Schoenauer M1900 as introduced at the Paris World's Fair of that year.
Rifles other than the Mannlicher Schoenauer M1900, M1903, Y1903 and variants are seldom encountered with the 6.5X54MS chambering and it does not interchange with others.
However, the 6.5X54 MS was directly descended from the 6.5X53R (6.5X53.5R) as used on several variants of Mannlicher's M1891 military straight pull (
ruck-zuck) rifles and carbines. They are ballistically identical when loaded with the 160 grain RN projectile and to original specifications. Straight pull Mannlichers chambered in the 6.5X53R can be found in sporting form, usually built by 'bespoke' British gunmakers. 'Sporterized' military arms also exist.
The only difference between 6.5X53R and 6.5X54 MS (rimless) is that the rimmed version feeds through 'en bloc clips' (the original Mannlicher Packet Loading System) while rimless 6.5X54 MS feed through the Schoenauer rotary magazine. Other than case head they are the same cartridge.
Mannlicher Packet Loading System (En Bloc), loaded with spitzers
Schoenauer Magazine with 6.5X54 MS Cartridges
The M1900 was produced as prototype and 'sales samples' in effort to gain military contracts for the Mannlicher Schoenauer which resulted in contracts with the government of Greece. When Osterreichische Waffenfabriks Gesellschaft Steyr began production of the Greek contract in 1905, commercial sporting rifles entered production as the venerable M1903 as well as the M1905, chambered for the proprietary 9X56 MS, which would be joined in turn by the M1908 (8X56 MS) and M1910 (9.5X57 MS), each proprietary chamberings.
Greek military Mannlicher Schoenauers, all of which chambered the 6.5X54, were Y1903, Y1903/14, Y1903/14/27 'Breda', 'System 1930'. and variants.
'Greek' Mannlichers
In the not so distant past, military surplus Y1903 through 'System 1930' rifles and carbines were readily and inexpensively found at sporting goods shops across the U.S. and elsewhere. Many have since been 'sporterized' by craftsmen of skills ranging from 'Bubba' to the finest of gunsmiths.
For what purpose do you seek an M1903?
If you want the finest and intend to treat her well I'd advise searching for an original, unmolested, 'low miles', original pre WW2 M1903. If you desire 'optics', find one with a vintage 'scope already mounted that suits you.
The 'civilian' Mannlicher Schoenauers are considered by many to be among the finest commercial sporting rifles and carbines ever produced.
If you intend to travel with it, there was a marvelous Take Down Model built by Steyr (OWGS) on the system used by Westley Richards (I have an M1910 TD).
If you're looking for one to use hard I'd recommend finding an 'action' from or a semi complete Y1903 or variant and build your dream rifle from there. They are still around though not as inexpensive or plentiful, but the receiver and magazine of a Y1903 is identical to that of an M1903.
The cost of a newly manufactured MS receiver would surely exceed that of a complete 'project' based on a Y1903.
With the rising collector interest and diminishing supply, however, complete and unaltered 'Greek' Mannlichers are becoming expensive and it's a bit of a shame to cut up an original.
The 'Greek' carbines do make relatively light, accurate, short, and tough brush and bush rifles just as they were built. The same can be said of Straight Pull Mannlicher carbines (stutzen) which take the rimmed 6.5X53 R cartridge.
Ferdinand Ritter von Mannlicher
BR.