Check with the Provost Marshall at your CURRENT post AND at your California assignment. They will give you the up-to-date info and help you make arrangements for the LEGAL transportation/storage of your firearms. Military personnel are "exempt" from certain state laws, but you need to find out exactly what you need to do.
If you plan on shooting your "California-illegal" firearms while assigned in California, be sure to have your military I.D. with you, and any other documents that specifically denote the "exemption" that you have.
Registered "assault weapons" are now LEGAL to shoot in many Bureau of Land Management locations. Even though BLM is a "federal" agency, they are required to uphold certain "state" laws. At one time, the registered "assault weapons" could only be fired at "authorized ranges" (wherever those are?). The BLM was NOT an "authorized range" a couple of years ago, but that has since been changed. Californians who have REGISTERED "assault weapons" can shoot them in many BLM territories, but it is advisable that you have your registration documents available. Otherwise, you may be "detained" for an investigation.