1 ruble thickness

Hello. I bought a Russian 1 ruble coin from 1897 some time ago. I measured it, and while the weight and diameter were alright, I measured thickness of 2.32 mm. That seemed a bit odd as the official thickness on numista (and elsewhere, as far as I can tell) is 2.7 mm, although this coin has a fair bit of wear on it.

To research this further I measured the only other ruble I have from Russian empire, from 1891, which numista and other sites seem to claim should have thickness of 3 mm. I am fairly certain that this ruble is genuine, as I got it from my grandfather a long time ago. Again, weight and diameter were what I expected, while it had a thickness of 2.44 mm. This coin also has wear on it, although not as much as the first one.

Now, I know that back in the day, people at the mint probably did not care that much about the thickness of the coins they produced, as long as other characteristics were fine. Or at least they probably did not in Finland, which was a part of Russian empire. Either way, I am asking if anyone else has measured rubles of Alexander III or Nikolai II, and if their measurements seem in line with the cited thickness of the coins (2.7 for Nikolai II, 3 for Alexander III)?