Finnish M27 Question

I have recently picked up a Finnish M27 and had a few things that I could not find elsewhere on the internet. Hopefully you can fill me in. On the left side of the receiver there is a number that I do not know the origin of. The number is 81873 with what looks like a sideways 4 before that. I have been told on another forum that it could possibly be a civil guard district number. I was under the impression that the M27 was the Army's version of the rifle and the M28 was the Civil Guards. There is also no SA stamp anywhere on this particular rifle. It was made in 1940 and the receiver was made at Sestroretsk in 1900. The bolt matches the barrel. I have attached a few pictures and any observations you may have would be greatly appreciated. Thanks in advance.

The serial number on the receiver is likely not a Civil Guard number, although it is possible that it is an early one. Your 1940 Tikkakoski m/27 is from the last year of production and was likely put together with whatever parts the Finns had available that year, or later during the Continuation War. It's a very nice piece from one of the more uncommon years of m/27 production.