Can't give you a definitive answer, but for what it is worth I've had a small hatchet in my pannier several times when crossing into/out of Russia. My baggage was never inspected, so no one ever saw it, but I don't think it would have been a problem if they did find it--after all, they are tools rather than weapons.
But these border crossings can be pretty capricious, and particularly if someone liked the hatchet they might say you can't bring it in, so I wouldn't get too attached to it.
If you are really worried about it and don't expect to need a hatchet prior to Russia, you could just buy one here, they are pretty common.
|