SKS adapters
Chris--For almost all things SKS, I rely on DC Engineering, in Detroit. Website:
www.rifletech.com
They market an adapter for AK mags, and also modified mags that fit with no adapter.
There is one model of SKS that uses AK mags with no adapter; it is the Chinese SKS-M I believe. It is rare and expensive. (Well, expensive for an SKS, anyhow.)
Now, having said that, IMHO, other than that special Chinese SKS, ALL SKS's work best with their own built-in 10-round mag, which you can load with stripper clips that are cheap, easily obtainable, and with practice, quick and reliable. Or you can of course singly-load the mag.
"The word" that you hear almost universally, is that trying to use a removable mag in an SKS is expensive, awkward, unwieldy, difficult, unworkable, requires tweaking, etc, etc.
With a 10-round mag of its own that works like gangbusters, I fail to see the attraction in a removable mag. But, to each his own.