One thing I noticed that looked a bit fishy is that the inscription, in Russian, reads "...from the workers of the Tula factory." Note that the proper name should be "Tula Weapons Factory" and the missing word is "oruzheinogo" in transcription. Why it was not included in the engraving may be simply because of the lack of space, but who knows. Everybody knows of the huge Tula weapons production complex.
This reminds me of a faked samovar I saw in Germany in the 1980's. I was in the US Army at that time and a colleague came back from a vacation in Turkey with an "antique" Russian samovar. Examining the various stamped markings, which typically denote the various prizes the maker has won for his products, I saw numerous spelling errors. So the samovar was either a complete fake, or an old worn samovar that had its markings enhanced by someone with only rudimentary knowledge of Russian. On another occasion I saw a faked Russian icon, also with spelling errors, although in Old Church Slavonic. The kicker was that on the back side of the icon were glued sheets of old Russian newspapers printed with the post revolution orthography. By then it was well known that Gulag prisoners were making these fake antique icons.
Regarding the OP's original photo, even if it is a fake, it would still be valuable simply because so much skill and effort went into it. Oddly, there is a lucrative market for certain faked renaissance paintings, particularly by a certain German painter, and this is because of the amount of skill invested ino making a fake.