Perhaps you obtained your guns so long ago that you were not required to transfer them through an FFL.
Or perhaps the "many guns" that you own are all long guns without pistol grips and you brought them with you when you moved from another state where you bought them from private parties.
If neither of those is true, then you just might want to look into the laws of Kalifornia on the chance that you are in violation of the laws and may be in jeopardy of being convicted of a serious crime.
Very interesting and a good possibility. I did buy them long ago.
My home was robbed a few says ago and I cannot find one gun in a separate bedroom. I’m planning on buying another ... and may be surprised.