I load two things for the Nagant revolver.
First is .32 S&W Long brass (which works fine in these but it will swell them a bit). I load a moderate (unpublished load) charge of fast powder and use the Lee 311-093-1R bullet cast from recycled range scrap in my six-cavity moulds, lubed with ALOX and unsized. These are good plinkers.
I also load a Hornady #0 buckshot pellet (.320") in 32 Long brass with a charge of 800-X from my .25 acp load. These are accurate out to 20' and can almost be shot indoors without a backstop. Great gallery load! I seat the pellet all the way to the case mouth and it looks like a wadcutter with a domed top. The seater die sort of swages the pellet down to oblong a little to fit the 32 brass.
I also am trying out the PPU nagant brass loaded with a Lapua 98-gr .314" lead wadcutter. For dies I'm using a Lee .30-carbine die set with a Lee .32 ACP seater/crimper adjusted all the way up. It works, but needs messing with.
If you need brass, the PPU stuff is good, doesn't split often, and if people leave it at the range, you are lucky! I've got about 300 pcs of it freebie so far that way. Otherwise I would stick to .32 S&W Long/ .32 Colt New Police brass- but that's not much easier to find.