M40 Russian Helmet?

[Disclaimer]

Hi, I bought a soviet steelhelmet couple years ago from Pietari. I was wondering if it was m40 or the infamous czech m53. Here is couple really bad pictures, hopefully someone can get something out of them.
In the lining there is small square with OTK-20 written in it. And in the rim there is 1492 stamped on to the back.

[Dimas]

Hello,
This is Soviet SSch-40, but from that pictures very hard to recognize the date of producing, from the first look it's look like post -war made, but may be I'am wrong. If you post a better pictures then I can say you my final opinion.
With regards,
Dimas