It is legal for active-duty military to register assault weapons (according to the CA definition) prior to moving to CA by applying for a Military Assault Weapon Permit (MAWP) through CA DOJ. If you leave the military while in CA, they need to get out of state either by sale, storage, etc. but...
Active Duty Military Can Register Assault Weapons And Bring Them To CA!
If anyone needs more specifics, IM me and I'll pass on the folks at CA DOJ who handle this.
If you're already stationed here, you're boned for new sales.