You can own lots of fun stuff (full autos, destructive devices, sbrs, supressors, etc.) as long as you pay the tax stamp ($200 a pop) and file the correct paperwork. Generally it takes many months to process the paperwork. If you can purchase a firearm, you can usually purchase a class 3 weapon.
Oh yeah, and you gotta sign away your privacy (i.e. no warrant necessary to enter your home), and get police permission to purchase the weapon.
Also, depending on the set-up you want, multiple tax stamps may need to be paid. Say you want an sbr and a supressor, 2 tax stamps would apply.