Sent the specs on the .22 Magnum AR-15 to the California Attourney General and they said that as long as it's not a ZIP gun, it's OK. Their approval is due to the inner mechanics which are NOT compatable with the centerfire upper. In other words, relieing on the INNER mechanics of the weapon to render it "not an AR-15" instead of exterior limitatiosn like the FAB-10. The inner mechanicle differences are un-noticable from the outside of the gun and you would never know about them unless you took the gun apart and do not affect the function so in that respect, behaviorally ( and compatability wise ), it's a full fledge .22 Magnum AR-15 that takes full size detachable mags and everything ( just like the DPMS.
Those of you who are not familiar with the background, look at my other thread/s on this subject.
Once I am done and have it inspected, I'll post pictures of the rifle, the letter from the attourney generals office and how to do this modification ( which will require advanced gunsmithing skills.