The 7.62 x 39 is a good, mild shooting cartridge that is suprisingly accurate in a well made fiream. However, when you get to taking about the 7.62 x 39 you often run into the barrel/bullet size problems. If Rossi chambers in 7.62 x 39 what size is the barrel bore? If it is 7.62 (.311) then surplus ammo will shoot well in it and it will be cheap to shoot. However if the bore is .308 like the Ruger Mini-Thirty than accuracy will go in the crapper and many steel jacket ammo's will be real barrel bulgers as you cram .311 bullets down a .308 bore. Also .311 bullets to reload are not that common and the selection, weights, ect are limited.
If the Rossi barrel is .308 you can get 7.62 x 39 die sets with .308 neck adapters and take advantage of the wide supply of .308 bullets out there to reload. Of course one wonders why a 30-30 barrel might not be a better option. It has greater case capacity, nearly identical performance, better long range energy retention (handles heavier bullets better) and is a standard .308. Add to that it is a rimmed cartridge and will extract fron the Rossi barrel easier. Rossi/NEF single shots are not famous for posistive extraction and the rimmed cartridges seem to do a lot better.
If you want a good 7.62 x 39 single shot just take the gas piston out of your SKS. It will fire fine and you just pull back the bolt handle and release to load the next round.
