I don't know anything about the muzzle device, but since this SKS has only the fixed magazine, I
believe it is OK. The CA DOJ assault weapons list is here.
http://ag.ca.gov/firearms/forms/pdf/awguide.pdf
I don't know what you mean about CA not recognizing C&R's. You can buy C&R rifles here in CA without a FFL.
Sincerely,
Marc