I actually have just gone through this delima after my father past away.
We were told by the DOJ after SB23 passed to just register each gun twice, once in his name, and once in mine. My application was rejected because I didnt turn 18 by Aug. 16th 2000 (where they came up with this date, I have no idea). I turned 18 in Sep. of 2000, and was denied registration and after making numerous phone calls and writing letters, the DOJ just said too bad, thats the way it is.
So now my father passed away, I inhereted his gun collection, and had to dispose of a pair of AR-15s.
I sold them to a CA assault weapons dealer. They put the rifles up for sale to LEO, and out of state dealers.
I didnt get much for them either, but it was better than just turing them in and getting a pat on the back for being a good citizen. I just put the money towards a gun the my dad and I had been looking at for awhile before he died, a Springfield MC Operator!