Wolf offers a 7,62x54 match ammo that has won many European shoots I highly recommend you give it a try. I did see it offered on one of the sites on the net. I would say to use the sellier & bellot 7,62x54 in FMJ but i have heard there other ammo is inconstant with the crono(7,62x25) so the powder charge maybe all diferent. But i haven't heard anything about their rifle ammo on the crono yet. I know the only thing left is reloading then its the bullet weight and the burn rate of the powder to match the twist of rifling in the barrel if you want awesome accuracy. You could checkout
www.gunboards.com then click on mosin-nagant.net they do have some info on Finnish mosins. BigBill
I shoot surplus ammo in just about everything sometimes and i just clean it good with the orginal Army G.I. Bore Cleaner and i never had a problem yet. Plus i never trust any imported ammo wether its new or surplus we just never know. I clean all my guns the sameway even my modern guns too so i never make a mistake. Nowadays I trust no one as to what primers they are using.