Re: Is an AR-10 A4 bought in 1997 legal in California
DROS paperwork does not constitute registration, so unless you also registered it with the DOJ in California prior to the ban, it will not be legal to own in CA.
In order to keep it in the state, you will need to replace the lower receiver with one not banned by name in CA. Armalite and it's subsidiary Eagle Arms are both banned by name, but Armalite pattern receivers from Noveske, Aero Precision, and a few others I can't remember right now are legal to own in the state as long as they are configured properly.
Proper configuration for an AR type rifle to be legal in CA will go one of two ways:
A) Install a magazine lock with a 10 round magazine in place, creating a "Fixed" or "Non-Detachable" magazine. Options are available that allow magazine release, provided a tool of some sort is needed to remove the magazine from the rifle, which is legal under the definitions provided by state law. The tip of a bullet is considered a tool for this, so a device known as a "Bullet Button" has become pretty popular out here. It allows the mag to be removed by requiring the use of a bullet tip or other small tool to actuate the release button.
B) Remove the pistol grip and flash hider, and install a buttstock designed with an integrated hand grip like the U-15 stock:
http://www.californiarifles.com/
It's ugly as sin, but will allow you to use a standard mag release as well as any high cap mags you had before the ban took effect.
Much more information can be found on the
http://www.calguns.net/ wesite.