I load cast lead for my Mosin.
I have 3 different loads I use so far, using 2 different bullets cast from Lee molds.
7 grains of red dot or promo with CTL-160-312-2R (designed for 7.62x39) without the gas check.
13 grains of red dot or promo with same bullet, with a gas check.
13 grains of red dot or promo with C-185-312-1R, with a gas check.
All shoot decently at 25 yards. The heavier loads shoot just as well at 100 yards. Your zero will be quite a bit lower, so you will have to play with the elevation settings on your rifle (600-700 meter setting works good for the light load above at 25 yards for me).
I cast my own bullets, so I haven't the foggiest for buying them pre-cast. Just make sure you slug your barrel and get bullets .001 or .002 larger.
I find that the 13 grain loads I could shoot all day, since there's very little recoil. It's cheap as hell, too. The 7 grain loads are even cheaper, at half the powder and no gas check. They're really only good for practicing breathing/trigger work or off-hand shooting, but they have NO recoil. It's like shooting a .22 with a heavy stock. I lube all the bullets with liquid alox and neck-size only when I can get away with it (I have a burr in the chamber I need to have removed). You can use 2400, but you'll probably end up using more powder for very small performance (accuracy) gains, and thus your cost per round will go up. My biggest factor is cost, so I use the cheapest possible powder (promo), but your requirements may vary.
I heartfully suggest using lead in your mosins. Check out Ed Harris' articles on "the load" and "cast bullets in military rifles". A little googling or searching here on THR should lead you to links. Very good information.