Rubicon Models do maybe a dozen figures armed with SMGs. You could cut off the original weapons and replace them with rifles as needed (they're multipart figures) - as I've done with a few of mine.
Black Tree Design also had a whole Kickstarter of figures in snow suits. With the caveat though that there's a slim chance of receiving your order if you do go with those.
Heer46 also has a few figures. Only like six or so.
Particularly you may want to look at figures wearing Amoeba camouflage suits. Which can have a similar cut to snow suits (more so depending on how the suits were manufactured). Just paint them up white and they do the job. Artizan, Warlord, Great Escape Games, and possibly West Wind come to mind for those. Bad Squiddo also do some female figures in those suits if you want some variety (i.e. female support elements attached to a male platoon).
Oh and I've seen some manufacturers doing Finnish models in snow suits. Which would be perfectly useable as Soviets with head swaps.