This is a Magpul® PMAG® D-50 AR-10 LR 308/SR-25 7.62x51mm/.308 Win 50-round drum magazine.
Combining rugged, lightweight polymer construction with corrosion-resistant steel springs, these Magpul AR-10 drum magazines are engineered to meet the same strict standards as Magpul’s popular D-60 drum magazines for AR-15 rifles. Since their introduction over a decade ago, Magpul’s PMAG magazines have gradually become the industry standard for lightweight and ultra-reliable combat magazines. Seeing adoption from major armed forces including the U.S. Army, Air Force & Marines, PMAG magazines are the ultimate upgrade for your AR-10 rifle. Magpul’s D-50 magazines give you maximum long-range firepower, with twice the capacity of a standard AR-10 mag without any added length. They’re designed to be left loaded for long periods of time without reducing reliability or service life. Note that many extended magazines can be difficult to load at first, but that springs will gradually wear in over time. Stiffer springs ensure reliable feeding and function. We recommend adding a magazine loader to your order for quicker loading and maximum trigger time.