Units 439, 445, 611: DS-39 MMG
Currently available from June 1939 to June 1940.
Around 200 of these guns were captured from Soviet troops by Finns in 1941- so the weapon was still in use at that time. Also I have seen photos of German troops using captured DS-39 mahcine guns.
I would extend the end availability date to perhaps December 1941 ?
Regarding the star availability date:
In Finnish literature I have only seen the Maxim machinegun listed as in use by Soviet infantry in Winterwar. Also in the Jaeger Platoon website there is a mention of the production of DS-39.
"Tula Arsenal was the only manufacturer of DS-39 machinegun, it manufactured 10,345 of them between June of 1940 and June of 1941. From those 10,345 machineguns it made 6,628 in year 1940 and 3,717 in year 1941."
So perhaps the start date should be June 1940 instead of June 1939?
Online sources:
http://www.jaegerplatoon.net/MG2.htm#762KK39
http://world.guns.ru/machine/rus/ds-39-e.html
http://en.wikipedia.org/wiki/DS-39