It seems to follow the standard Russian marking practice, but the slide serrations look like they don't match up to the date on the pistol (1966); by that time, I believe that they had already gone to the finer slide serrations. Both the slide and the barrel should be marked with the same serial number, so you can see if they actually match. Even if they don't the pistol should still be safe to fire, it just won't be as desirable to a collector.
