Russian platoon organization (Imperial Army, Red, White, whoever...)

[MartinR]

I would presume that  in the reality they simply took the available riflemen and divided them up into four (or three) platoons between the available officers and sergeants. So depending on the size of your company you could have platoons of anything from 20 to 50.

That was pretty common practice in both WW1 and WW2.

Cheers
Martin