I have been reloading for the 7.62x45R for my 91/59 and a SAKO M-39. I discovered early on, reloading for other Mosins, that flat based bullets offer the most consistent accuracy. If your rifle of carbine has muzzle wear or damage boat-tail bullets will generally not shoot well. I have had great accuracy using Varget or IMR 4350 with both Speed and Hornady 150gr .311/.312 bullets. Like the 303 British you can extend case like by neck sizing your brass for a given rifle.
Towards thee I roll, thou all-destroying but unconquering whale; to the last I grapple with thee; from hell's heart I stab at thee; for hate's sake I spit my last breath at thee.