The 30-round rifle magazine has been the standard high-capacity magazine for more than three decades. These devices are used by the military and police around the world, and can be found accompanying popular civilian rifles like the AR-15. Online, they can be purchased for as little as $8 apiece, The Trace reports. The reason for the 30-round magazine’s popularity is simple: It hits a technological sweet spot. Magazines with larger capacities, while available, are often cumbersome and unreliable. Their size makes lying prone difficult. And the number of moving parts mean they often jam. As a result, larger devices have remained more novelty than practical accessory for over a century.
That’s now changing. Spurred by the opportunity to land lucrative military contracts, American-based firearms accessory companies have developed a new generation of high-capacity magazines. The devices are compact, lightweight, and strong, holding anywhere from 40 to 100 rounds, allowing their users to fire far more before having to reload. Experts say these larger models are growing in popularity, and will soon dominate the civilian market.