I have a couple of Mosin rifles,my M44 is a 1945 round receiver Izhevsk refurb & my 91/30 is a 1933 HEX receiver Tula stock only referb both of which I ended up doing a cork bedding and stock refinish on.
The M44 has a .312" groove bore while the 91/30 has a .313" groove bore. On a scale of 1 to 5,1 being an excellent bore and 5 being the worst I rate both of mine according to pics I've seen at a 2 the rifling is strong and the bore is nice an smooth. I've only shot surplus and component jacketed bullets I reload in the M44. I have several types of surplus ammo Bulgarian old brass case light & heavy ball ammo made back in the mid 50's which doesn't shoot well at all in the M44 as is,bullet dia. is at .310" and it's loaded fairly hot. I ended up breaking down most of it an either reducing the charge weight by 2.0 grs. resizing the neck and reseating the bullets all to the same OAL an groups shrunk down to about 3" at 100 yds. which I though was fairly acceptable.
The Bulgarian HB cases were of much better quality brass and had been stored under better conditions so I broke some of that down as well an replaced the bullet with a Speer .311" Hot Core SP bullets a friend gave me form his old 303 British days for hunting purposes since at the time no commercial 54r hunting ammo other than Norma at $1 was available.
My favorite surplus ammo is the Yugoslavian brass case 182 gr. .311" FMJ which is all copper jacket lead core ammo,it shot under 3" right out of the box so I put that away in my stash for a rainy day.
I also have Russian an Bulgarian steel case light ball ammo made in the 70's & 80's but it's still in the sealed tins. Pretty much ever since I started casting my own bullets I hardly ever shoot a jacket bullet these days although I have plenty stashed away for a rainy day. I can pretty much do anything with a cast lead bullet I can do with the more expensive jacketed bullet as to target shooting or hunting. My two favorite bullets for either Mosin are the Lee .312" 160 gr. tumble lube or the Lee .312" 185 gr. RN bullets both which use a gas check. In the past I've used a mix of Alox / Johnson Paste Wax tumble lube for most all my rifle bullet but for the standard grease groove bullet I now have a RCBS lubesizer and I powder coat as well but I haven't had much time to experiment with the PC'ed rifle bullet as of yet.
Alliant 2400 has been my go to powder for general purpose shooting in the Mosin's 16.0 grs. is a very accurate load in both rifle for mid range velocity around 1600 fps. For HV cast loads which is going to top out at around 2K fps. accuracy wise with 185 gr. bullets in the 1:10 twist bore I'm working up my load using H-4895 currently up to around 1700 fps. using 33.0 grs. which is only around 78% load density. I should be getting close to Max velocity/RPM/accuracy at around 90% load density. Once I find that load with the standard cast lubed gas check bullet I can work on some PC'ed versions of that bullet.
Some unlubed 185 gr. bullets
Some 160's loaded and ready to shoot.
Test group out of the 91/30 using the Lee 185 gr. bullet cast for wheel weights and water quench straight from the mold gas checked,lubed with 2500+ and sized to .314"
My $100 91/30 after the refinish.
My M44 after the refinish.