All of the rifles in my list other than the Soviet-Sino variant and the Long barreled M59 Yugo, would most probably come back from Vietnam. No East German, NVA Type 1, or North Korean SKS rifles have ever been reported to come back, be imported, or "brought back" from any other location.
Those three do not need paperwork to be bringbacks, but the paperwork sure adds a ton of value if it is there.
Darin