The 1999 law covered any semiautomatic centrefire rifle with a detachable magazine and any of six "military-style" features: 1) a flash suppressor, 2) a grenade launcher or flare launcher, 3) a thumbhole stock, 4) a folding or telescoping stock, 5) a forward pistol grip, or 6) a pistol grip that protrudes conspicuously beneath the action of the weapon. But regulations issued by the California Department of Justice defined "detachable magazine" as "any ammunition feeding device that can be removed readily from the firearm with neither disassembly of the firearm action nor use of a tool being required." The regulations specifically said "a bullet or ammunition cartridge is considered a tool," which left the door open to "bullet buttons" that release the magazine when you insert a cartridge into them. Since guns with bullet buttons did not technically have detachable magazines, they could legally include the features that offended the sensibilities of California legislators.
Gun controllers saw that creative solution as an outrageous loophole, which they sought to close with S.B. 880 (a.k.a. A.B. 1135). The new law makes any of the six detested features illegal on a gun "that does not have a fixed magazine," and it defines "fixed magazine" as "an ammunition feeding device contained in, or permanently attached to, a firearm in such a manner that the device cannot be removed without disassembly of the firearm action." Enter the Bullet Button Reloaded, a.k.a. the Patriot Mag Release, which allows removal of the magazine only when the rifle is opened, thereby disassembling the firearm action, as demonstrated by inventor Darin Prince in this video:
Prince, who describes himself as "the inventor of the original bullet button," says, "We have had the BB Reloaded in the wings for many years," which suggests entrepreneurs are at least a step ahead of gun prohibitionists. "The Bullet-Button Reloaded is hardly ideal," writes Dan Zimmerman at The Truth About Guns. "AR owners will have to release the rear pin on their rifle and tilt the upper receiver forward in order to drop the (10-round) magazine. But it's at least an option for keeping and continuing to use your long gun legally."
Zimmerman says "the moral of the story" is "there's almost always a way, and some enterprising individual will find it." More specifically, Prince's invention once again demonstrates the futility of trying to reduce gun violence by banning arbitrarily defined categories of supposedly intolerable firearms. Every time legislators pass an "assault weapon" ban, its supporters complain that the firearms industry is complying with it by making functionally unimportant changes. They think that's an indictment of sneaky gun makers; it is actually an indictment of misguided legislators.
[Thanks to Robert Woolley for the tip.]