[Ger-Poland-Volhynia] where is Poulin??

[gary and rhonda simpson]

Seasons greeting everyone!
I just received the 1940 registration (CDN) for my great uncle.  It gives his
birth place as Poulin Russia.  I tried Shtetl seeker but there are many
listed.  The only other clue I have is his brother's naturalization gave his
birth place as Warshau, Poland.  I though Poulin may be Poland, but on the
line below it gives Poland for his parents birth place (not town though).
It also gave him serving from 1896 to 1910 in the Russian military, 85th
regiment.  I know from family history that he was a payroll train guard during
the RussoJapanese war.
My questions are:  Any hints or helps on where Poulin may be, or possibly the
correct spelling of it?
and secondly, I tried a google search on "Russia" Military, History, 85th
regiment but all I get is WWI and WWII stuff.  Are there any good pre WWI
sites on Russian Military?
Any assistance greatly appreciated, as this is the only way I'm able to find
out about my grandmother as she didn't appear to leave any paper trail in
Canada, so I'm scouting out her brothers.
Rhonda Simpson
Canada