You can fix an SKS with a 30 round magazine, which is reloaded via 10 round stripper clips (don't do it though, they're unreliable).
In the case of the M1 and the SKS, the magazine, eg the device that holds the ammunition inside the gun, is the restricted item. The only difference is the magazine is not removed in the field, like with most other guns where that's how you reload.
In the case of the M1 and the SKS, the magazine, eg the device that holds the ammunition inside the gun, is the restricted item. The only difference is the magazine is not removed in the field, like with most other guns where that's how you reload.