Timeframe would be post 1850ish. As in, small Russia must be a leading great power by then. Any power in the top 10 of its world, for example, I would consider Germany, France, China, US, Japan, UK, Russia leading great powers of OTL 2016.
My best thought is you would have to have a very early POD, probably a Novgorod Russia. Because once Russia is formed by Moscovy, Russia will never stop trying to expand to the east, where their strong only opponent is Kazan (Sibir was never much of a threat and the Kazakhs were always divided). And once Russia starts eastward, they are going all the way to the Pacific. So the best thing to do is to change the center of Russia and where its ambitions and focuses are. If you have a Novgorod Russia, you can get Russia focused on the Baltic. This means Russia is going against several strong, independent foes which leads to a slower Russian expansion and smaller Russia in general. Also if Russia is focused on the Baltic and you strengthen the Cossack state you can keep Russia from expanding into the Black Sea. By 1850 Russia consists of the Estonia, Latvia, Finland, Lapland, Finnmark, Troms, Nordland, and Russian cores and some other bits and pieces. Russia's population is 30 million to 50 million I would say. It is heavily industrialized (coal and iron from Lapland and Russian core). And its great power status is built around its strong economy, dominance of the Baltic, and I dunno professional military.
Any other scenario ends with either too weak of a Russia or a still very larger Russia, but slightly smaller than OTL.
The problem is that Russia itself is quite large-- even it's core region is quite massive as it is arguebly the result of the Muscovite Annexation of Novgorod as Muscovy solidified itself as the sole "Russian" state. So the smallest I can see Russia being and still mantaining it's great power status is north of the estuary of the Volga and West of the Urals-- essentially, Russia proper. All in all Russia would still have most it's population and heavy industry but ofcourse loose out big on natural resources-- regardless, smaller countries have achieved such status. This could be achieved if the Tatars somehow managed to hold back the Muscovites/Russians from spreeding east entirely, which is improbable for long as Russia increases in power. Maybe the Golden Horde holds on to it's possessions much longer than in our time line? Perhaps being unable to spread East would make the Russians more invested in Western affairs meaning that Russia would look westward to expand-- which is considerably more difficult than just claiming sparesly inhabited land thus limiting their geographic area. This would also allow Russia to become more Western, perhaps allowing Russia to stay ontop of military technology and better asert itself as a great power whilst still being smaller. A scenario like this also brings up a lot of interesting questions as to what would happen to the Khanates and Siberia if they were not conquered by the Russians.