Remington was supplying several “Allied” governments already in late 1914 with M1899 and M1902 Rolling Block rifles, from Inventory. Canada bought some as “forager” rifles (I have a DCP marked M1902, almost Mint); the French had M1902 made in 8mm Lebel Rifle (“Modele 1914”) in both carbine and Musketoon fitting, for use by “Train”…Horse, Mule and Motor drivers.
The Serbians, of course, were a 7x57 nation, and their major modern Mauser was the M1899 Small-ring action ( a-la M1895) which used a “Wide” Mauser stripper clip, compatible with all the other "Mauser " commercial clips of the period (M91 through M97 Export types).
The JP Morgan (a US banking institution) buying agency would have factored all the British Government orders going to US Contract suppliers, irrespective as to whether they were for actual British use ( ie, United Kingdom) the other Commonwealth nations ( Empire then) or third party allies…Note the Russian Colt .45 Auto Pistol contract marked “Anglitski Zakaz—English Contract”. As the payments of all Wartime supply contracts from the US to “Britain” were done in Gold Bullion, not paper money or credit instruments,
a Bank would have to be the best way of doing it.
The Royal Navy was using a lot of “non-standard” calibres and models, as we have seen already from Ammo packets etc, and some very clear Photos from other Boards ( 7x57 M1912 Steyr Mausers from Ships turned over to the RN from Chile, etc and of course the Arisaka (".256" Rifles,) widely used by the RN for training etc.
As to the Remington sale of “repaired” rifles, a lot of Remington’s Customers in Latin America had contract clauses that Remington would occasionally “Trade in” worn or older Remington products for either New rifles or Ammo supplies. BY 1914, the Rolling Block design was "passe’ " and so Remington jumped at the chance of disposing of both Inventory new stock of M1902s and also “Old stock” of converted Remingtons and “trade-ins” from Latin America ( as the latter states “Upgraded” to Mauser made products.).
Remember, every single-shot Remington issued to a rear-echelon guard, driver, etc released a potential magazine rifle for use at the Front ( France, Britain and especially Serbia, which in 1915, lost virtually its entire “Mauser” inventory in battles with the Austro-Hungarians. Only supplies of Berthiers from France and “bought in” 7mm rifles from Britain to the Enclave in Salonika ( Macedonia, Now Greece—ex-Turkish province, freed in 1913 Balkan War).
So the 7mm ammo supply sounds very apropos.
As to the “low percentage” of clips ordered, the MG use of ammo was roughly 1,000 times that of Rifle ammo…a figure realised quite soon after WW I started…only the Germans had allowed for such a high usage of MG cartridges, all the other nations in WW I were still in the 1890s as far as ammo consumption for MGs was concerned…and even the Germans underestimated the actual high usage the MG usage rates at first…
It would be nice to find some original “Serbian” supply packets of Remington made 7x57 ammo…but I think the great wash of war through the Balkans in WW I and then WW II has eliminated all such possibility…especially since Yugoslavia converted to 7,9mm in 1924, and rebuilt a lot of its “Serbian” Kingdom 7mm Rifles to the new calibre…
Good excuse for an “Ammo archeological dig” at some WW I Serbian Front battle sites…one may be lucky, as “diggers” have been at Ypres with 7,62 Mosin Ammo there ( “Matrosen Division” areas, armed with M1891 Mosins and Maxim M1910 MGs).
More research into the British Archives will lead to more “mysterious” contracts for Ammo etc coming out of London to the US makers during 1914-1918.
Has anybody seen any USCCo 6,5x53R for Romania in 1916? Tillinghast did have a complete gauge set for the manufacture of this cartridge back in the 1980s for sale… it seems that when the Germans occupied Romania in late 1916, the ammo went as a Neutral sale to Holland ( same calibre); instead a contract for Locomotives from ALCO of Schenectady, NY, went to Italy ( “Le Rumene”) and these locos were still in General short distance passenger service in the post-WW II period.
Another “contract” was (from Italy?) to an unknown maker in New England, for over 10 Million sets of components for 10,4 Vetterli cartridges…to be loaded in Italy… For Italy or for the Russians???