The Russians have long been in love with the Maxim gun. One of the largest early users of the Gatling, but then moved to upgrade to belt-fed water-cooled Maxims in 1899, later contracting with Vickers in 1902 to manufacture the design in Russia, which led to the easily identifiable PM M1910 with its “Sokolov” shield.
Made in quantity, the gun was present in Port Arthur and with Gen. Kuropatkin’s forces in Manchuria during the Russo-Japanese War, then in WWI (where the Russian Army actually started the conflict with some 4,000 machine guns of all type, a fact not commonly known).
The Russians and later Soviets used them in armored trains:
In anti-aircraft mounts:
From Tachanka gun carts, a practice honed in the Russian Civil War.
The M1910 continued to see much service through WWII and then was shuffled to the reserve and given away as military aid.
A popular mounting was in Russian naval service:
However, the Russians never threw anything away and lots of Maxims have been pressed into service in the Ukraine, where they no doubt still work just as well as they did at Port Arthur.