My trigger is stiff as hell on the Mosin, but I don't really want to mess with it since I have basically no experience in doing so.
See the "Bubba Free Accurizing of the Mosin Nagant" link I posted above, it tells a decent way to improve the trigger fairly easily. Here is the link again.
Take a look (well, feel actually) and see if there are any burrs or rough spots where he mentions in that article. If there is, you can very carefully try and smooth them out with emory paper. Don't go nuts, just try and remove any obvious rust spots, and it may help quite a bit.
On edit: Forgot, another good reference on Mosin Accurizing: