Finnish police reported in late October that weapons sent to Ukraine had appeared among criminals, first thinking that corruption in Ukraine was to blame. This was a big victory for Russia who had been spreading fake news about that Ukraine selling weapons they got to criminal networks, but it turns out that when Russia captures Ukrainian soldiers with western weapons, Russia can’t use those as they do not have ammunition (the old 7.62×51 vs 7.62×39 syndrome) for the weapons more than what the Ukrainian soldier had on them when captured.
The only way Russia can profit from them are to sell them to criminals in Western Europe, as they will have access to the right ammunition to use the weapons, Russia gets USD/EUR which they need for buying computer chips from the black market and at the same time they destabilize the west with heavy armed criminal networks.
The current trade routes are Finland and the Baltic countries, as they share border with Russia or Belarus and it’s possible to smuggle the weapons over the border, specially when the Russian border guards are helping in the smuggle operation.