When California attempted such nonsense a mere 2.33 % of semi-auto owners 
complied. A wonderful demonstration of a justified Civil Disobedience. 

"As a one-year registration period draws toward an end on Dec. 31, 1990 only about 7,000 weapons of an estimated 300,000 in private hands in the state have been registered. This non-compliance has virtually nullified the first step of a March 1989 law that set the pattern for similar attempts to limit ownership of assault rifles in other states and in Washington." 

http://www.nytimes.com/1990/12/24/us/california-gun-control-law-runs-into-rebellion.html?pagewanted=all