What kind of question is this?
At this point in time, obtaining an "assault weapon" via any method is illegal (according to our masters). The field is wide open.
You can still, legally, purchase Curio and Relic SKS's at this time (saw a few in the stores recently). I believe that only the Romanian ones qualify at this time.
You can buy a M1 Garand through the CMP and as any WWII vet can tell you, it's not an "assault weapon." Really, no detachable mag, no AW.
Wonder if I can still buy a FN-49 since it has a fixed, 10-rnd, mag...