Ross Rifles making the rounds: Spanish Civil War

Of the multiple types of nonstandard rifles sold by the Soviets to the Republican Spanish, the comparatively low numbers and varied types suggest that these rifles were miscellaneous variants used, inventoried, and stored following the end of the Russian Civil War. In addition to a number of Austro-Hungarian Mannlicher and German Mauser rifles, English Lee-Enfield and Canadian Ross Mk.III rifles were also likely sourced from ex-White Russian stocks which fell into Soviet hands following the defeat of the Whites in 1923, who had received them as aid earlier in the Russian Civil War during Allied intervention efforts, There exists a book of the various arms used in the Spanish Civil War which incorrectly identifies a Ross MkIII as a "Lee Enfield".

The question would be whether they sent all they had or only some? If all, then presumably what they used in WWII or later came from the Baltic States in 1940.

We know the Soviets were using Mk.IIIs for target shooting and some experimental sniper work in the late 20s or early 30s. Russian sources have said this continued as long as their stocks of .303 ammo lasted, so was ammo provided to the "Republicans" with the rifles or sourced somewhere else?