Compared to Boxer primers, Berdan is not "readily" reloadable. First off, you have to acquire the right Berdan primers (there are several different sizes and types) NONE of which has been common or easily available in the US for generations. Since there is almost no market for them here, very few ever get shipped to the US, and that was before all the Euro nations got on the "arms control" bandwagon.
Second, if you DO somehow get the right primers, decapping requires special tools, either prying out the fired primer, or pushing it out hydraulically. I did see one set up to blow out the fired berdan primer using a boxer primer, but that's hardly economical, even before boxer primers got scarce and expensive.
Berdan primed brass in commonly available calibers is, essentially, scrap brass once fired.
The SKS was designed for Soviet troops, first fielded in the closing months of WWII. It is rugged, reliable with Soviet mil spec ammo, simple enough for poorly trained conscript peasants to use and gives (generally) minute of man out to as much as 300 meters in the hands of a good shot. The round is slightly less powerful than the .30-30, though the generally lighter pointed bullets give it a little bit better trajectory.
It may be described as "over gassed" but the point of that is so it works, under all conditions, including extreme dirt and extreme cold. IT is not particularly "reloader friendly" it was never made to be, but it will run well enough on properly tailored reloads.
Nominal bore size is .311" but individual rifles can vary.