I saw this book about two years ago.
It was about a whole town that time travels from the 1970s to 1800s and they use their advanced technology to become mercenaries. I think in the first book in the series they go to Russia and fight in a war there.
Stump the Bookseller
New format, same book stumper solving.
This sounds as if it might be 1632, the first book in a series. However, it’s not the 1800s where the town ends up, it’s –surprise! — 1632, and they end up in the middle of the Thirty Years War, with the advantages of some modern technology. The town’s name is Grantville, West Virginia.
http://en.wikipedia.org/wiki/1632_series
This might be 1632 by Eric Flint, in which Grantville West Virginia gets tossed back in time to the Thirty Years War in Germany. If so and you use a e-reader, amazon has it for free or the Baen Free library(http://www.baenebooks.com/c-1-free-library.aspx) has it for different formats.
Maybe S.M. Stirling, Nantucket series?
I’m going to say that sounds suspiciously similar to 1632 as well and I’m inclined to say that’s probably going to be it, though as someone else said the dates and places don’t match up. Then again, 1632 is part of a much bigger book series in a shared universe, so one of the sequels to it by author Eric Flint and his fans might have involved 1800s Russia in some way (I’ve only read “1632”, but, for example, “1636: The Kremlin Games” sounds like it might be a close fit as well).