I’m not familiar with the SKS-type rifles; I was under the impression they had detachable magazines.
I’m pretty sure the enbloc 8-round clip for the Garand would be interpreted as a “detachable ammunition feeding device”.
The SKS can be modified to take detachable mags. As manufactured, it has a fixed magazine.
The vast majority have a ten-round fixed magazine, loaded through the top via stripper clips. There's a guide slot for the clips at the front of the bolt carrier. The SKS-D and SKS-M models were modified to accept detachable AK-47 mags.
Im pretty sure the enbloc 8-round clip for the Garand would be interpreted as a detachable ammunition feeding device.
Unlikely. The "feeding device" (spring-loaded follower) is integral with the rifle. Of course, that's not to say that BATFE won't come up with some new and astonishingly stupid rule.
A few SKS's have been "modified" to accept some AK magazines,it can be done but not easily, and with the Garand "clip"... maybe, but it is not really an "integral" part of the weapon, more like a "speed loader", but hey that hasn't stopped the gun grabbers before!