Chile contracted with Vickers for the supply of the cruisers prior to 1914…the ships were almost complete in 1914 at the outbreak of war; the British promised Chile that their ships would be returned at the Cessation of Hostilities or replaced if lost in the meantime.
The Chilean Rifles were Steyr (Austro-Hungary)-made Mauser M1912 Chilean contract rifles, cal. 7x57 Mauser. Vickers like any self-respecting Arms maker, had connections (Financial and commercial) with all the Arms makers of Europe…Hence the Mausers as part of the Arms Locker complement of the Chilean ships…Chile was a “Mauser” Nation.
Another example is the socalled “Vickers Luger” Pistol, for Holland in the early 1920s…Vickers’ association with Germany’s DWM allowed the supply of assembled Luger Pistols, carrying the Vickers name, to Holland in 1923, from parts made/accumulated by DWM during WW I, a matter formally prohibited by the Versailles treaty (all such stocks of parts, guns etc, were supposed to surrendered and destroyed by the Allied Control Commission.
Arms Lockers usually held enough rifles on board to arm all the enlisted personnel of the crew, so several Hundred Rifles were involved per ship.
As the Ships were commissioned into the Royal Navy, they would have had the Mausers removed, and replaced by Lee-Enfields of earlier Models, as was common in the Royal Navy. The Mausers were used for “Mine Destruction”…Picked marksmen on small ships would “shoot off” the “Horns” of Sea Mines to explode them, once the Mine cable had been cut and the Mine floated to the surface.
The Royal Navy also used large quantities of 6,5 calibre Japanese Arisaka Rifles for training and arming small ships (Kynoch made ".256 " Ammo)
At war’s end, the Cruisers were returned to the Chileans (HMS Canada in Particular, and I think one other was a replacement, as the original had gone down in battle)…But the Mauser rifles were not supplied with the “redelivered” Chilean Cruisers…they got Ross Rifles, in .303 calibre ( M1910 Model, Mark III; those which had been withdrawn from Flanders because of problems with ammo tolerances etc.)
The Chileans were not in a position to complain, as Steyr could no longer supply Mauser rifles…the original ship’s Mausers had “disappeared” into the Surplus stream, and so the “Directorado de Armada” (Naval Directorate) in Chile numbered the Ross Rifles (& bayonets) with a new , “DA” serial Number…I have “DA 252” with matching Number bayonet…Ross Rifles in WW I were not Factory Numbered, a “store/issue” number being applied to the Woodwork, not the metal, upon delivery to a Depot.
So Chile can be said to be a (limited) user of .303 ammunition over the period 1919-1960s, when the Rifles were finally surplussed off…mine still shoots very well, despite its “LC” enlarged chamber, when I use close tolerance (ie Canadian or Australian) ammo. It is supposed that Chile continued to buy ammo (both 7mm and .303) from British Suppliers from 1919 onwards (examples of Kynock 7mm Chilean contract ammo are common)
As to the marking “Mine” etc, the ammo was probably loaded with care, to get good accuracy (lots selected on “Figure of merit” sytem): shooting a Mine Horn of about one to two inch diameter, six inches long, at a distance of over 100 yards, would take some accuracy…using Open sights. And the mine is Bobbing up and down in the water…very good shooting is required.
As shown, the label is a typical ISAA approved Service Label in layout and style. All ammo supplied to the British War Office carried such labels if it was made in Britain or the Commonwealth (then Empire).
A simple packet and a photograph have just enlarged my knowledge of Chilean ship’s armament three times…
Regards, Doc AV