A set of British MGs to match the German MGs would really round out the two armies in Great War.
Russian PM1910 team as well
.... I think the French Hotchkiss Mle 1914 would be a better start, though a Russian PM1910 would be useful even for bleeding edge modern/altmodern wargaming (like given they are still in use in the current war in Europe, you could probably use them for Ghost in the Shell cyberpunk gaming though you would need to do conversion work).
