Copyright issues aside, taking apart a St Petersburg casting would be akin to using a $5 American Eagle to buy ice cream, wouldn't it?
I'd look first among the various Russian figure producers' websites, and on eBay, for those who also sell via eBay, for the castings. Many pieces painted by the Russians can be found in their unpainted form, and I have seen examples of the same casting painted in various styles and to different levels of quality (some of the figures that Sergei Ilyashenko sells as Lead Army, for example).
That doesn't necessarily apply to every single figure every produced, of course, but it might be less costly to locate and buy the casting, and then bash it and paint it, rather than to strip, bash and repaint one painted to the highest Russian standard.
Prost!
Brad