Sulaco:
Full-auto or multi-round burst weapons are still available - if you were LEO and had authorzation from your Chief, you could get one for ~1,000. If you were in the Military, they'd issue you one, gratis.
If either of the above don'y apply, your only hope for one in California is to fall into a specialized class.
You could become a Class III dealer, and all that implies. However, the licensing and regulatory requirements (at least in LA County, and possibly elsewhere in the state) would prohibit you from operating a store out of your home, or operating it as a hobby.
You could have full-auto weapons, and rent them to studios for productions. But the uses are very limited, and I believe that you have to have a Class III license to do this.
You could purchase one on behalf of a corporation, for security, but I don't know what's involved with this. As a corporation, you get more leeway than as a citizen, but the details are sketchy.
You could get a SA weapon, and have it illegally converted, or try for an "import" from a less rigorous locale. But this runs the risk of a long sentance if caught.
Unfortunately, Sualco, the odds are against you. If I had a lick of sense, I would have bought a few FA weapons before Reagan signed the ban, and things tightened up.
Having failed to show the foresight to do that, we can either accept that FA weapons aren't in our future, move to a more accepting state, or hope for more liberal laws in the future.
But in California, here and now, we're screwed.